Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html Phone 617-495-7244/7440/7444 (for emergency use only) SUPERNOVA 1998T IN IC 694 D. Balam, University of Victoria, reports the following precise position for SN 1998T, obtained with the 1.82-m Plaskett telescope of the National Research Council of Canada: R.A. = 11h28m35s.97, Decl. = +58o33'35".9 (equinox 2000.0). A nearby star (R = 17.3) has position end figures 34s.00, 31'21".4. Visual magnitude estimates: Mar. 15.795 UT, 14.3 (K. Hornoch, Lelekovice, Czech Republic); 19.772, 14.3 (Hornoch); 19.776, 14.4 (M. Plsek, Lelekovice, Czech Republic); 20.96, 13.9 (K. Sarneczky, Agasvar, Hungary). (C) Copyright 1998 CBAT 1998 March 21 (6844) Daniel W. E. Green Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html Phone 617-495-7244/7440/7444 (for emergency use only) SUPERNOVA 1998T IN NGC 3690 H. Yamaoka, Kyushu University; T. Kato, Kyoto University; A. V. Filippenko, University of California at Berkeley; and S. D. Van Dyk, Infrared Processing and Analysis Center, California Institute of Technology, report: "The position of SN 1998T reported on IAUC 6844 is incorrect; the position derived from an R-band image taken at the 0.95-m Ayabe Astronomical Observatory reflector on Mar. 18.5 UT (by M. Yamamoto) is R.A. = 11h28m33s.16, Decl. = +58o33'43".7 (equinox 2000.0; based on GSC positions). Comparison with the nearby star (R = 17.3, IAUC 6844) on the Ayabe image shows that SN 1998T was not brighter than R = 15.5, and was possibly at R > 16.0, much dimmer than the reported visual magnitude estimates around this epoch (see below). This discrepancy could be due to contamination by the host galaxy or to misidentification: some galaxy catalogues, including RC3, incorrectly identify IC 694; the designation of Wynn-Williams et al. (see IAUC 6830) is also incorrect, and it was the basis for originally assigning SN 1998T to IC 694. NGC 3690 (Markarian 171) is an interacting pair of galaxies, and IC 694 is a small E/S0 galaxy located 1' northwest of NGC 3690; these three compose Arp 299. Note that NGC 3690 produced several supernovae in the past decade: SN 1992bu (IAUC 5960), SN 1993G (IAUC 5718), and the probable radio supernova reported on IAUC 4988. Keck-2 spectra of the brightest knots, obtained by Filippenko on Mar. 27, show that SN 1998T is the only clear supernova in NGC 3690 at this time. A chart of SN 1998T is available at http://www.obs.misato.wakayama.jp/~ayabe/michi/ayabe.jpg." D. Balam reports that a check of his CCD image (cf. IAUC 6844) shows no point source at the position specified above; he suggests that SN 1998T may be hidden in the scatter caused by the galaxy core on his frame. K. Hornoch and M. Plsek, Lelekovice, Czech Republic, reported on Mar. 28 that observations made on Mar. 26 show nothing at the correct position of SN 1998T down to visual mag 16, and conclude that their earlier observations (cf. IAUC 6843, 6844) were not of SN 1998T and should therefore be disregarded. ########################################################################### TAKEN FROM HIBBARD \& YUN 1998, in preparation ``A 180 kpc Tidal Tail in Arp 299". \Foot{}{There is some confusion as to the naming of this system, which is addressed separately in the appendix. In the following, I use the naming convention of the vast majority of researchers since 1959} \section{Appendix: Who is IC 694?} There seems to be some confusion in the printed and electronic literature as to which systems actually comprise Arp 299 (e.g.~IAU circ 6859; NED). Arp himself does not offer many clues, and even confuses the matter by incorrectly designating Arp 296 as NGC 3690+IC 694 in Tables 1 \& 2, while giving Arp 299 no further designation. However the description in Arp's Table~1, and the order of his figures (Arp 296 appearing next to other bridge-tail systems) makes it clear that Arp published the pictures under the correct number, and gave them the correct description in Table 1, and just got the ``Designation" switched in both tables. The description given for NGC 3690 in {\it New General Catalogue of Nebulae and Clusters of Stars} (Dreyer, 1888, Mem. RAS, 49, Part 1) reads ``pB, pS, vlE 80$^o$, pgbM, S, st sf nr" which translates as ``pretty bright, pretty small, very little extended at PA=80, pretty gradually brighter towards the middle, small stars south following near". According to the NGC ``pretty small" means a diameter of 50\as-60\as, and this radius would incorporate much of the brighter parts of the system (including the nucleus of the Arp 299E). Given that the five highest surface brightness objects are within 7\as\ of source B2 in Arp 299W, through a small telescope this object must have looked like a single nucleus centered on source {\bf B} in Fig.~1 with a cloud of surrounding nebulousity, i.e.~it is unlikely that two nuclei could have been discerned. It therefore seems pretty certain that the original designation refers to the entire Arp 299 system, although only one nucleus was identified (corresponding to Arp 299W, what we have been calling NGC 3690 in the above). Therefore whether NGC 3690 should strictly apply to the entire system, or to only the western system, depends on if you believe galaxies are identified by their nuclei or their integrated light. We remain agnostic on this point, and from here investigate which object was designated as IC 694. The earliest and clearest association of IC 694 with Arp 299E can be traced to Vorontsov-Vel'yaminov, in his {\it Atlas of Interacting Galaxies} (Vorontsov-Vel'yaminov 1959), where Arp 299 appears as VV118a-e. Source VV118a is the galaxy to the East (what we have been referring to as IC 694), VV118b the system to the west (what we have been calling NGC 3690), VV118c is the compact spheroidal 1\am\ to the NW, and VV118d \& e are bright HII regions in the outer disk regions to the NW. In the accompanying table to the Atlas, VV118a is identified as IC 694, NGC 3690 as VV118b, and sources c,d or e have no other designations. The vast majority of researchers since have followed this designation. The description for UGC 6471/2 in the {\it Uppsala General Catalogue} (Nilson 1973) first brings up the question of whether the designation of IC 694 with Arp299E is correct: ``Arp 296 (identified as NGC 3690 + IC 694 by Arp) are faint objects north-preceding UGC 06471 + UGC 06472, magnitude approximately 17 and 21 identification of IC 694 uncertain, may be a small object north-preceding and inside the outer parts of the double system". [The use of the name Arp 296 is immediately attributed to Arp's error in making his tables, discussed above]. NGC 3690 and IC 694 were discovered by different observers (Herschel 1786, {\it Phil.~Trans}, part I; and Swift, 1893, MNRAS, 53, 273, respectively). Swift had access to Herschel's list of Nebulae, as is apparent from his discovery description: ``close D with 3690=H 247.1 suspected with 132, ver.~with 200." which translates as ``close double with NGC 3690 = object 247 of list I of Sir William Herschel. Suspected at 132x magnification, verified at 200x". This is translated in the {\it Index Catalogue of Nebulae} (IC, Dreyer, 1985, Mem.~RAS, 51, 185) as ``vS, forms D neb with I247", which translates as ``very small, forms double nebula with no.~247 of list I of Sir William Herschels". ``very small" translates as 10\as-20\as\ diameter, which is on the large side for the NW spheroidal (\FWHM\about4\as). There is no definition of the term ``double" in the IC (Dreyer states ``the system of abbreviated description ... has been in use so long that it is unnecessary to enter into a lengthy explanation of it.."), and perhaps this is where the confusion lies. Certainly with todays knowledge we would call Arp 299E+W a double, and if anything the spheroidal to the NW as a possible companion. However, is this how Dreyer, Swift and the Herschels used the term? At this point, it is quite instructive to look at an earlier photographic representation of the Arp 299 system which does not show the galaxies saturated. For this, we refer to reader to Plate 1 of Morgan (1958, PASP, 70, 364). In this figure, the NW spheroidal appears as a very faint fuzz well separated from and much dimmer than either of the two interacting disks, which appear as distinct objects. So the question is, when Swift identified IC 694, did he subdivide the NGC 3690 entry, or add a further nebulousity to the NW? The position for IC 694 (epoch 1860) is given as 11:20:44 +59:20 in the IC, while the NGC position for NGC 3690 is 11:20:45 +59:19, i.e.~IC 694 lies approximately 1\am\ to the NW of NGC 3690. This sounds like pretty conclusive evidence that IC 694 indeed refers to the spheroidal to the NW. However, given the reference to I~247 rather than NGC 3690, it is not clear if Swift worked from the NGC position [**SEE EMAIL FROM MALCOM THOMSON BELOW - ARGUES THAT SWIFT DID INDEED WORK FROM THE NGC; SUPPORTED BY HAROLD CORWIN**]. The I~247 references Sir William Herschels un-reduced observations in the 1786 {\it Phil.~Trans}. Additionally, Dreyer remarks in the introduction to the IC that Swifts positions are ``generally reliable within one or two minutes of arc, but larger errors occur occasionally, and ... it is generally very difficult to be certain that the latter are not identical with the old ones." We also learn from Dreyer that Swifts observations were taken through a 16\as\ refractor at the Rochester Observatory. Since the NW galaxy is 3 mag fainter than either of the disk galaxies ($m_B$=16.2 mag from CCD observations reported above), is it even possible for Swift to have seen the NW companion? [**STEVE GOTTLIEB SAYS YES, SEE EMAILS BELOW**] If not, it is likely that he simply resolved NGC 3690 into two separate condensations of nearly equal luminosity, adding a separate catalogue entry for the the second system. [**AMATEUR OBSERVERS ARE WORKING ON THIS**] A similar super-classification appears to have happened in the case of NGC 4861/IC 3961 (Arp 266). It is nearly impossible to prove this issue conclusively one way or the other, and I therefore choose to follow the vast majority of researchers and use the designation introduced by Vorontsov-Vel'yaminov (1959), concluding as Sulentic \& Tift (1973, RNGC) that ``Any further question as to which objects Dreyer was referring to can only be of historical interest". Special thanks to Harold Corwin, Malcom Thomson, Steve Gottleib, Bill Vacca and Dennis Webb for many useful discussions on this issue. ======================================================================== EMAIL EXCHANGES (edited some irrelevant comments): From DenJWebb@aol.com Wed Apr 15 00:17 EDT 1998 From: DenJWebb Date: Wed, 15 Apr 1998 00:14:00 EDT To: bwilson2@ix.netcom.com, bwilson@ruf.rice.edu, jsancho@pdq.net, larrymit@ix.netcom.com, goldberg@sccsi.com, akelly@ghg.net, binder@onramp.net, MDelevorya@aol.com, drako@ix.netcom.com, cbr@ghg.net, RFMJr@aol.com, polakis@indirect.com Cc: jhibbard@NRAO.EDU Mime-Version: 1.0 Subject: Arp Observing Challenge X-Mailer: AOL 3.0 16-bit for Windows sub 38 Content-Type: multipart/mixed; boundary="part0_892613641_boundary" X-Lines: 139 Status: RO Content-Length: 8155 John Hibbard of the NRAO asked me for some amateur assistance in resolving a historical question about the identity of one of the galaxies involved in Arp 229. The issue is whether IC 694 (catalogued by Swift in 1893) is the western galaxy of the merging pair (the eastern galaxy being NGC 3690) or a small mag 16.2 spheroidal object (MGC+10-17-2A, in my estimation) embedded in the northern part of the merging pair. Most sources consider IC 694 to be the larger merged object. The issue is posed in IAU circular 6859, reporting a SN in Arp 299. Dr. Hibbard is writing a paper on Arp 299 and is researching the ambiguous history of the cataloging. Swift was a skilled observer using a 16-inch refractor (unknown focal length) in dark sky. Dr. Hibbard asks whether expected performance of such an instrument and visual observer would indicate which of the objects Swift catalogued. It occurs to me that visual observation of this complex with equivalent-performing amateur refractors might shed light on the question. Here is the deal: document visual observations of the object with equivalent instrumentation (giant dobs masked down to 16", big SCT's, real big refractors). Comment on your observations relative to Swift's description. Provide an email of your observations to Dr. Hibbard and me. If the results are usable, he might include them in his paper. If not, we have still explored an unusual object and confronted the problem of galaxy naming. Attached is a Megastar chart of the objects. Send observations to: Dennis Webb, denjwebb@aol.com John Hibbard, jhibbard@NRAO.edu Clear skies, Dennis From sgottlieb@telis.org Thu Apr 16 21:08 EDT 1998 Mime-Version: 1.0 Date: Thu, 16 Apr 1998 17:56:53 -0700 To: DenJWebb@AOL.com, jhibbard@NRAO.EDU, hgcjr@ipac.caltech.edu, scoeandlross@sprintmail.com, bas@lowell.edu, brianc@fc.net, watcher@freenet.edmonton.ab.ca, rbunge@access.digex.com, Steinicke-Streifeneder@t-online.de, malcolmt@4dcomm.com From: Steve Gottlieb Subject: Observation of IC 696 Cc: bwilson2@ix.netcom.com, bwilson@ruf.rice.edu, jsancho@pdq.net, larrymit@ix.netcom.com, goldberg@sccsi.com, akelly@ghg.net, binder@onramp.net, MDelevorya@AOL.com, drako@ix.netcom.com, cbr@ghg.net, RFMJr@AOL.com, polakis@indirect.com, raycash@AOL.com, redshift@pipeline.com X-Lines: 132 Status: RO Content-Type: text/plain; charset="us-ascii" Content-Length: 6406 Hi, folks I wasn't on the original mailing list, but this message was passed along to me by an observing buddy (Ray Cash) and the identification problem for the supernova was mentioned by Brent Archinal. The question of the identification of IC 694 was raised a few years back by Harold Corwin (see e-mail message below) and likely solved. Subj: Re: IC 694 Date: Fri, Mar 3, 1995 2:46 PM EST Speaking of IC 694 -- this is one that still needs a good visual verification. Most professionals these days assign I694 to one of the two closely interacting galaxies, and N3690 to the other. I don't think this is right. N3690 is both objects, and I694 is the small companion an arcmin north-west of the brighter pair (the companion is VV118c, and the pair is VV118a,b. VV 118d,e are knots apparently associated with a. The Arp Atlas -- it is Arp 299, not 296 as labeled -- shows the whole thing very nicely). Swift's description is tantalizing: "vS, close double with 3690 = H 247.I, suspected with 132, ver[ified] with 200." Harold Corwin -------------------------------------------------------------- I was able to take a look with my 17.5" f/4.4 on April 1, 1995. The skies were moderately dark (mag 6.0) observing on the east side of Mt Hamilton (significant light dome from San Jose) and the observation was made at 220x and 280x. Here is the jist of my observation and reply to Harold: This unusual system appears moderately bright, fairly small, elongated E-W. The appearance is confusing with two very small "knots" in a common halo elongated E-W. On the W side is a fairly bright virtually stellar "knot" which is probably the nucleus of the brighter member N3690. There is a small fainter extension on the following end (IC 694?) which is weakly concentrated. The two components are not individually resolved. With averted vision and concentration an extremely faint spot was intermittently visible about 1' NW (M+10-17-002?). Although I could not hold it steadily, this extremely small object was repeatedly glimpsed. In the Rosse observation from 1852, Jan. 27 the description reads "Neb. divided into two parts, F(aint) appendage np about one diameter distant. It appears that the "faint appendage np" was the extemely faint companion which I glimpsed as the separation and orientation is correct. If Dreyer was using this description for IC 694, then IC 694 = M+10-17-002? I don't have a copy of Swift (X) which Dreyer also attributes to IC 694. What description did Swift give? Perhaps someone can reobserve this system and verify if the faint component 1.1' NW of the interacting pair is visible. It probably falls a bit below the CGCG cutoff. Steve Gottlieb -------------------------------------------------------------- Harold responded with the following comments on the identification: Date: Wed, Apr 12, 1995 3:40 PM EST From: hgcjr@ipac.caltech.edu Thanks, too, for your observation of N3690/I694. Swift's description is brief: "vS, close D with 3690 = H 247.1 suspected with 132, ver. with 200." If we assume that Swift used the NGC position for N3690 as his reference here, then the small companion to the northwest most likely is I694. The NGC position is 11 25 56, +58 49.6; Swift gives 11 25 49 +58 50.1 for I694. Swift's offset from N3690 is -7s, +30''. This is at least in the right direction; the real offsets are -4.6s to -6.2s (depending on which component of N3690 we use), and +1.0'. This also matches Lord Rosse's description of the "appendage" to the north-west. So, I think that we have finally pinned down I694. Your observation suggests that it is indeed possible to pick up the galaxy with a scope the size of Swift's, so I'm going to go with it. Here are the positions (B1950.0 as usual): Galaxy RA Dec Source IC 0694 11 25 37.8 +58 51 15 HCo (offset from 2 GSC stars) N3690w 11 25 41.40 +58 50 15.4 GSC N3690w+e 11 25 42.42 +58 50 16.9 GSC N3690e 11 25 44.06 +58 50 19.0 GSC All this, by the way is Arp 299 (not 296 as in Arp's index). Arp 296, however, is close following: Arp 296n 11 25 56.4 +58 52 15 HCo (same 2 GSC stars) Arp 296s 11 26 01.4 +58 50 10 HCo (same 2 GSC stars) Thanks again for looking at this. On to the next puzzle. -------------------------------------------------------------- So, the small companion to the northwest is visible in the same class scope that Lewis Swift used, although it was a difficult object. This is not inconsistent with a number of the faintest Swift discoveries that I've observed with a 17.5". Still, it would be helpful if other observers with similar aperture could verify my observation from three years back. It's very possible that from a darker site, IC 694 would not be a marginal object as I indicated (I haven't revisited this system). Steve Gottlieb From jhibbard Fri Apr 17 17:23:57 1998 To: DenJWebb@AOL.com, hgcjr@ipac.caltech.edu, scoeandlross@sprintmail.com, bas@lowell.edu, brianc@fc.net, watcher@freenet.edmonton.ab.ca, rbunge@access.digex.com, Steinicke-Streifeneder@t-online.de, malcolmt@4dcomm.com, sgottlieb@telis.org Subject: Re: Observation of IC 696 Cc: bwilson2@ix.netcom.com, bwilson@ruf.rice.edu, jsancho@pdq.net, larrymit@ix.netcom.com, goldberg@sccsi.com, akelly@ghg.net, cbr@ghg.net, binder@onramp.net, MDelevorya@AOL.com, drako@ix.netcom.com, RFMJr@AOL.com, polakis@indirect.com, raycash@AOL.com, redshift@pipeline.com X-Sun-Charset: US-ASCII Content-Length: 4661 X-Lines: 83 Status: RO > From: Steve Gottlieb > Subject: Observation of IC 696 Steve, thanks very much for the work on this. This mail is directed primarily to Steve and Harold, although I am cc'ing everyone on Steves distribution. Quotes are from Steves email, referencing a 1995 correspondence with Harold. Harold> Thanks, too, for your observation of N3690/I694. Swift's Harold> description is brief: "vS, close D with 3690 = H 247.1 Harold> suspected with 132, ver. with 200." If we assume that Swift Harold> used the NGC position for N3690 as his reference here, then Harold> the small companion to the northwest most likely is I694. Harold> The NGC position is 11 25 56, +58 49.6; Swift gives 11 25 49 Harold> +58 50.1 for I694. Swift's offset from N3690 is -7s, +30''. Harold> This is at least in the right direction; the real offsets Harold> are -4.6s to -6.2s (depending on which component of N3690 we Harold> use), and +1.0'. I concluded from Swifts reference to H 247.1 rather than NGC 3690 that Swift was not working from Dreyers catalog. H 247.1 is a reference to list I of Sir William Herschel from 1786 (as you undoubtably know). Additionally, in the IC Dreyer remarks that Swifts positions are "generally reliable within one or two minutes of arc, but larger errors occur occasionally, and ... it is generally very difficult to be certain that the latter are not identical with the old ones." However, the NGC was published in 1888, and Swifts discovery in 1893, so he certainly could have referenced his observations the the NGC position. I just found it hard to be certain based only on the quoted positions. A main piece of information I am missing is: how was the term "Close Double" used by Dreyer, Swift, the Herschels, and other observers of their time? Rosse's 1852 discription "F appendage np" seems much more on the mark than "close Double" for the NW object. Certainly by todays standards we would not consider the NW galaxy a close double to NGC 3690. Is 1 diameter "close"? The NW gal is just outside one diam, according to the NGC description for NGC 3690 (which gives a diameter of 50"-60" for NGC 3690). This is all I could find about the terminology, from Dreyer: "the system of abbreviated description ... has been in use so long that it is unnecessary to enter into a lengthy explanation of it.." I suspect Harold is well versed the earlier terminology. My library lacks the GC (Sir John Herschel, 1864) that Dreyer hoped NOT to replace! Two things make me slow to conclude that the NW galaxy is indeed IC 694: (1) An early photographic image of Arp 299 taken by Morgan (1958, PASP, 70, 364, plate I). This is a photographic exposure with a 60", and I therefore assumed that it is even better than could be obtained by eye with a 16". In this picture Arp 299E,W are clearly distinct, and the NW object a very small, much fainter fuzz well separated from them. Based on this, *I* would be much more inclined to split NGC 3690 into two entries than to add the NW object as a "Close Double" to NGC 3690. But of course I am a 1980's observer, not an 1890s. Examination of the Arp atlas shows that many closely overlapping systems similar to Arp 299 were given two catalog designations (e.g. Arp 81=NGC 6621/2, Arp 93=NGC 7284/5, Arp 123=NGC 1888/9, perhaps even Arp 244=NGC 4038/9). While Herschel may have been unable to separate the two in 1786, Swift should have been able to in 1893. Are there any other examples of Swift splitting an NGC object that anyone is aware of? If he never did, then perhaps it *IS* the NW object that he identifies. (2) The size given for IC 694 in the IC ('vS'=10"-20", is several times larger than the diameter of the NW spheroid (FWHM~4"), and about the right size for Arp 299E. Some remarks on Swifts observations: Previous to 1892, Swift put out nine lists (I-IX) each of 100 nebula. In his list X, he only listed 60, writing "the large and increasing number of electric street lights of this city [Rochester NY] has rendered the search for these faint bodies almost useless, and may compel me to entirely abandon their quest and enter upon some other line of work". His next list, designated as list (X) by Dreyer and which contained the IC 694 discovery, only listed eight objects. This leads me to believe perhaps his site (Rochester, NY) was not the best in the world. Thanks again for the info. -john From malcolmt@4dcomm.com Fri Apr 17 19:51 EDT 1998 Date: Fri, 17 Apr 1998 16:50:34 -0800 From: Malcolm Thomson X-Mailer: Mozilla 4.03 (Macintosh; I; 68K) MIME-Version: 1.0 To: jhibbard@NRAO.EDU, hgcjr , "sgottlieb @Å" Subject: IC 694 : Content-Transfer-Encoding: 7bit X-Lines: 51 Status: RO Well John I see that you have come across one of the historical observers, Swift, whose positional data for his credited objects often drive present day investigators up the walls. Actually in the case of IC 694 it would appear that he is unusually fairly correct in the coordinates he gives. To begin with I believe that in arriving at his coordinates for his IC 694 he did employ its positional association with NGC 3690 and that this was based upon Dreyer's NGC position for H 247-1. Wm. Herschel's coordinates are very poor, being based upon separations of - 28 tmin 13 tsec and + 2.0 degrees of arc from the star 66 UMa, which would result in a 1950 position of about 11hr 25m 09.3s + 58 52' 36" His son John Herschel in his Slough Observations gives a much better, but not precise position of 11hr 25m 53.6s + 58 49'.2 (1950) and it is obvious that it was John's coordinates that Dreyer used in his NGC which are 11hr 25m 54s + 58 49'.5 (1950) At the time Swift observed IC 694 (1892), Dreyer's NGC position for that same year for NGC 3690 would have been 11hr 22m 34s + 59 08'.6 and we see that Swift's 1892 coordinates for his IC 694 are given as 11hr 22m 30s + 59 09'.2 or about 04 tsec preceeding and 0.4 arcmin north of where he would believe NGC 3690 to exist and these relative positions come close to only one object, the faint companion galaxy north-west of NGC 3690. Bigourdan at the Paris Observatory, using a 12.4 inch refractor, measured excellent coordinates for the double system NGC 3690 giving a number of measurements for the main brighter parts and employing the 10th magnitude star which lies south east of NGC 3690 as his reference star. He arrived at an excellent position for NGC 3690 of 11hr 25m 42s + 58 50' 21" (1950), which indicates that Dreyer's coordinates are off by about 12 tsec RA and about 51 arcsec dec. but Bigourdan did not make these precise measurements until the year 1901 or 9 years after Swift's observation, therefore it would seem conclusive that Swift's coordinates are predicated upon the data given by Dreyer for NGC 3690 as before the time Swift made his observation I know of no other given coordinates published for NGC 3690. This then would seem to me to strongly suggest that if IC 694 exists as a separate galaxy and not part of the NGC 3690 combination it would have to be the object north preceding and as we now have confirmation from Steve Gottlieb that he was able to see this object visually with a similar size telescope to that used by Swift I am in favor of such an identity. Cheers, Malcolm From jhibbard Fri Apr 17 21:13:39 1998 To: DenJWebb@AOL.com, hgcjr@ipac.caltech.edu, scoeandlross@sprintmail.com, bas@lowell.edu, brianc@fc.net, watcher@freenet.edmonton.ab.ca, rbunge@access.digex.com, Steinicke-Streifeneder@t-online.de, malcolmt@4dcomm.com, sgottlieb@telis.org Subject: Re: Observation of IC 696 Cc: bwilson2@ix.netcom.com, bwilson@ruf.rice.edu, jsancho@pdq.net, larrymit@ix.netcom.com, goldberg@sccsi.com, akelly@ghg.net, binder@onramp.net, MDelevorya@AOL.com, drako@ix.netcom.com, cbr@ghg.net, RFMJr@AOL.com, polakis@indirect.com, raycash@AOL.com, redshift@pipeline.com X-Sun-Charset: US-ASCII Content-Length: 1832 X-Lines: 39 Status: RO I apologize to all who are on this thread against their will. This is the last time I will cc anyone who does not explicitly request to be kept abrest of developements. > From malcolmt@4dcomm.com Fri Apr 17 19:51 EDT 1998 > > To begin with I believe that in arriving at his coordinates for his IC > 694 he did employ its positional association with NGC 3690 and that this > was based upon Dreyer's NGC position for H 247-1. ...snipped for brevity... > At the time Swift observed IC 694 (1892), Dreyer's NGC position for that > same year for NGC 3690 would have been 11hr 22m 34s + 59 08'.6 and we > see that Swift's 1892 coordinates for his IC 694 are given as 11hr 22m > 30s + 59 09'.2 or about 04 tsec preceeding and 0.4 arcmin north of where > he would believe NGC 3690 to exist and these relative positions come > close to only one object, the faint companion galaxy north-west of NGC > 3690. ...snip... > This then would seem to me to strongly suggest that if IC 694 exists as > a separate galaxy and not part of the NGC 3690 combination it would have > to be the object north preceding and as we now have confirmation from > Steve Gottlieb that he was able to see this object visually with a > similar size telescope to that used by Swift I am in favor of such an > identity. Pretty convincing. Are you using the position and precession values given in the NGC to arrive at your epoch 1892 coords for NGC 3690? I was not so convinced by Steves observational description, and perhaps he can convince me. For any others who have or who might observe this object, can you make out the NW spheroidal *if you didnt already know it was there*? If I get a good firm affirmative on this, I will consider the matter closed, and that astronomers have been misidentifying this object since it was designated VV 118 in 1959. -john >From jhibbard Fri Apr 17 21:15:07 1998 Sorry for last email - was attempting to delete it after Harolds last reply, but sent it instead! In short, the case appears to be closed. -john From hgcjr@ipac.caltech.edu Fri Apr 17 20:57 EDT 1998 From: hgcjr@ipac.caltech.edu Date: Fri, 17 Apr 1998 17:53:19 -0700 To: jhibbard@NRAO.EDU Subject: NGC 3690/IC 694 observations Cc: DenJWebb@AOL.com, bas@lowell.edu, scoeandlross@sprintmail.com brianc@fc.net, watcher@freenet.edmonton.ab.ca, rbunge@access.digex.com, Steinicke-Streifeneder@t-online.de, malcolmt@4dcomm.com, sgottlieb@telis.org, bwilson2@ix.netcom.com, bwilson@ruf.rice.edu, jsancho@pdq.net, larrymit@ix.netcom.com, goldberg@sccsi.com, akelly@ghg.net, binder@onramp.net, MDelevorya@AOL.com, drako@ix.netcom.com, cbr@ghg.net, RFMJr@AOL.com, polakis@indirect.com, raycash@AOL.com, redshift@pipeline.com Content-Type: text Content-Length: 4835 X-Lines: 101 Status: RO Dear John, Since you've expressed some interest in the historical side of this, I'm going to dump the actual observations on you, starting with William Herschel who discovered the NGC object. Following those are some additional comments based on my 35+ years rooting around in the historical literature on nebulae. The observations: William Herschel (Phil. Trans. 92, 477, 1802; reprinted by Dreyer in 1912 in "The Scientific Papers of Sir William Herschel ...") I 247: 18 March 1790. 28m 13s preceding, 2 deg 0 min north of 66 Ursae. 2 observations. vB, pL, lE near par[allel], mbM. [me: very Bright, pretty Large, little extended parallel, much brighter in the middle] John Herschel (Phil. Trans. 123, 359, 1833) 896 = H I. 147 (sic): 11 19 01.6 30 31 52 (1830.0) B, R, pgbM. Query whether there be not a * excentric (sic) towards the sf side. (N.B. The obs makes PD = 31 deg, &c., but this must be a mistake. See next obs and my Father's place.) Sweep 323 (9 Feb 1831). [bright, round, progressively brighter in the middle] [RA not given, NPD =] 30 29 55. F, S, R, bM; has a * near, s. Sweep 226 (19 Nov 1829). Lord Rosse (Sci. Trans. Roy. Dublin Soc., Vol II, Series II, 1880) GC 2425 = h 896 = H I. 247: 1852, Jan. 27. Neb. divided into two parts, F appendage np [north preceeding] about one diam. distant. 1852, Ap. (sic) 15. Black line across, companion scarcely visible. 1860, Feb. 12. At 30 deg 30 arcmin +- and f last [Dreyer note:] (the neb. taken for [GC] 2408 [= NGC 3669]) about 1 minute is another, E n s, the s end of which is terminated rather abruptly and is there brightest, fading off gradually to n end. The south end is also the broader. (III. obs.) [= total of three observations]. Comments: That's all there was when Dreyer put the NGC together in the 1880s. Since he prepared Lord Rosse's observations for publication, he would have been aware of the "companion", so could have included it in the NGC along with the main object. There is nothing to indicate why he chose to ignore it; many other nebulae found by Lord Rosse near GC objects, and mentioned just as briefly as N3690s companion, are in fact included in the NGC. Just another little mystery. You've apparently seen Swift's original AN lists, as well as the 1893 MNRAS note announcing eight new nebulae, so I won't repeat any of that here. You are correct in noting that the comment "suspected with 132, ver. with 200" refer to the eyepiece magnifications. The notation for the brighter galaxy "H 247.I" is a bit unusual, but observers over the past 200 years have used all sorts of shorthand to denote WH's numbers. I would not put much weight on the size estimates in the NGC/ICs. Those are entirely dependent on the size and focal length of the telescope, the magnification, the seeing and transparency, how tired the observer was, and myriads of other variables. I've just run across NGC 3508 which WH called "small" and JH called "very large". Similarly, Herbert Howe (working with the Chamberlain Obs 20-inch refractor around the turn of the century) has this to say about NGC 6822 (D_25 is just over 10 arcmin): "On two nights I called this `vS,' while Barnard, who discovered it with a 6-inch refractor, called it `L.'" The only other historical observations of N3690 I've found are by Guillaume Bigourdan with the 30-cm refractor at Paris Obs. He makes no mention of the faint companion, but does split N3690 itself into two objects. He made 9 micrometric measures of the separation on three different nights in 1901, 1903, and 1911. They average out to +2.75 +- 0.12 seconds of time, and +2.3 +- 0.8 arcsec (std. devs., not root n errors; divide by 3 to get those) with the fainter component southwest of the brighter. Steve may have access to Father Hagen's WW1 era observations with the 16-inch refractor at the Vatican -- I have only example listings from the "Zone Catalogues" he prepared and the resulting "General Catalogue" that Father Becker assembled in the mid-20s. In the end, I would not put a great amount of money or prestige on IC 694s being the companion, but that is the most reasonable interpretation given the record. Enough of history; back to the supernova! Best wishes, Harold Corwin From DenJWebb@aol.com Sat Apr 18 00:24 EDT 1998 From: DenJWebb Date: Sat, 18 Apr 1998 00:23:06 EDT To: jhibbard@NRAO.EDU Mime-Version: 1.0 Subject: Re: arp 299 Content-transfer-encoding: 7bit X-Mailer: AOL 3.0 16-bit for Windows sub 38 X-Lines: 20 Status: RO Content-Type: text/plain; charset="US-ASCII" Content-Length: 933 Holy cow! What a startling thread! Several excellent observers with big visual instruments will study it at next week's Texas Star Party near the McDonald Observatory, so there will be the opportunity for further concordance or controversy. ... I hope this flurry has helped and not hurt your research. -Dennis From jhibbard Sun Apr 19 16:42:56 1998 To: bas@lowell.edu Subject: Re: Observation of IC 696 Cc: MDelevorya@aol.com, DenJWebb@aol.com X-Sun-Charset: US-ASCII Content-Length: 2401 X-Lines: 46 Status: RO > From bas@lowell.edu Sat Apr 18 20:48 EDT 1998 > > Given the historical record, I have no problem with IC 694 being > the tiny companion NW of the NGC 3690 pair. I have no problem with it, but it makes things messy, as far as the scientific literature goes. There are some 50+ references that refer to Arp 299E as IC 694, and only the UGC (and some conflicting notes and enteries in NED) that suggest that the NW companion is perhaps the proper identification. It would have been nicer to have reached the conclusion "we'll never know for sure, so may as well keep the popular designation", but one can't argue with the facts. > It may be of interest to mention my visual observations with a 15cm > refractor from the Lowell Anderson Mesa site. My limiting magnitude on > stars is V = 15.0-15.5 depending on the magnification, and the threshold > surface brightness is roughly muV = 24 per square arcsecond. My last > observation of the pair (but not IC 694) indicates clearly that the > NGC 3690 pair lie within a common envelope. For this reason I am not > surprised the pair were considered a single object for the NGC. Likewise, > that Swift caught the tiny companion seems reasonable. I have not been > able to find any magnitude estimates for it beyond VV's rough estimate--- > the USNO-A1.0 magnitudes for small galaxies are systematically bright. > With my 15cm the limit from true-dark sites at high power on galaxies is > roughly V-sub-T = 13.5, at least for high-surface-brightness objects > (Markarian galaxies and the like). IC 694 is probably in the V=15.0 to 15.5 > range as a guess, and that's within the range of a 40cm telescope just > from the ratio of apertures wrt the 15cm. > Hope this helps. > Brian I measure a B magnitude of about 16.2 mag from my CCD imaging (viewable at www.cv.nrao.edu/~jhibbard/a299/HIpaper/a299HI_fig01.gif - I'll have to redo all my labeling now!), so assuming a B-V=0.6 (I measure B-R=1) this puts it at 15.6, right about where you suggest. I am still hoping to get a eye-witness verification that someone can convincingly identify the NW object, without prejudicing their identification based on prior knowledge of its existence. Dennis Webb tells me that it will be targeted at the Texas Star Party next week. Thanks for the info! I think I will archive these correspondences at www.cv.nrao.edu/~jhibbard/a299/ -john From hgcjr@ipac.caltech.edu Mon Apr 20 14:20 EDT 1998 From: hgcjr@ipac.caltech.edu Date: Mon, 20 Apr 1998 11:17:05 -0700 To: jhibbard@NRAO.EDU Subject: Re: NGC 3690/IC 694 observations Content-Type: text Content-Length: 2374 X-Lines: 57 Status: RO Hi, John, > From jhibbard Fri Apr 17 21:44:57 1998 > > I don't fully parse the John Herschel observations - > do I take it that there is a second object about 1' N > of h 896? Or are these two separate observations of the > same object? If the former I don't understand why > he would say "has a * near, s" for sweep 226. > NGC 3690 has a star about 3' south, so it would be 4' s > of the NW companion. Why mention it for the latter but > not former? Or am I totally clued out here? They are two separate observations of the same object. Sometimes JH mentions nearby stars in one observation of a nebula, but not in others. This kind of inconsistency is one of the big problems in deciphering the old visual observations. Boiled down, the observations mean that JH saw only object here. Lord Rosse was the first to see the galaxy as double. > And what companion is Lord Rosse refering to in the notes to > his second 1852 observation? If the above answer is that there > are already 2 objects identified by John, then I guess that > also answers this question. If not, why would he call it > an "appendage" in Jan, and companion in April? It is the same object which he called the "appendage" in his first observation. Again, this kind of changeable notation is common in the old observations. Also, Lord Rosse was an amateur astronomer, so was doing all the observing for "fun." While he was careful to record what he saw, he also was fairly free in his use of language to make those records. > Also, can you tell me what "close double" means? In this case, probably less than an arcminute, but it could be anything down to a few arcseconds. This is yet another example of the free and easy style of the day -- a "close double" in one man's telescope might be an unremarkable wide pair in another's. Reading the old literature with "filters" more than a century or two thick can be tricky. This is why I am not fully convinced that Swift really did see the small galaxy to the northwest -- but I do think Lord Rosse did. On his authority alone, I'd be willing to assign the IC number to the companion. This has been an interesting case to revisit. Though the history rarely makes an impact on astrophysics these days, there are a few cases where it has been relevant. And I'm always pleased when folks are willing to spend a little time chasing this wonderful old stuff down. Best, Harold From sgottlieb@telis.org Tue Apr 21 21:39 EDT 1998 In-Reply-To: <199804192038.QAA00306@merger.cv.nrao.edu> Mime-Version: 1.0 Date: Tue, 21 Apr 1998 18:31:24 -0700 To: John Hibbard From: Steve Gottlieb Subject: Re: Observation of IC 696 X-Lines: 54 Status: RO Content-Type: text/plain; charset="us-ascii" Content-Length: 2562 >Steve - > >I wanted to clarify your observations reported above. > >Would you say that the NW object was persistent enough that it would >warrent a classification? ie, would you have been sure that you had >seen it w/o prior knowledge that it was there? > >Or do the Lord Rosse observations constitute similar "prior knowledge" >for Swift? > >-john John, As the observation was a few years back I don't recall it clearly, but my comments seem to indicate that I would probably have not noticed it without previously been aware of its existence. It sounds like I was using averted vision and concentrating on the spot where the NW companion was located: "With averted vision and concentration an extremely faint spot was intermittently visible about 1' NW (M+10-17-002?). Although I could not hold it steadily, this extremely small object was repeatedly glimpsed." I also stated in the same message to Harold (and other members of our NGC/IC sleuthing team) that "Perhaps someone can reobserve this system and verify if the faint component 1.1' NW of the interacting pair is visible. It probably falls a bit below the CGCG cutoff." So, although my visual "detection" was certain, I was hoping to get visual reports from others using similar sized scopes (just as you had suggested in the original message!). Unfortunately, there were no other reports forthcoming. I just searched my observation database and found at least three dozen Swift discoveries in my notes (over 5300 NGC entries) that I described as requiring averted vision, many of which I could not hold continuously. So, I've certainly found many of the faintest Swift discoveries to be difficult objects that I would not have "discovered" by sweeping in the area and not knowing of prior existence. Because of this, I have the highest regard for Swift's excellent observing skills (irregardless of his generally poor position), although this certainly does not "prove" that Swift's IC 694 refers to the north-preceding companion. It is ironic that based on Rosse's observation this galaxy should have made it into the NGC! Hopefully, this last interchange will lead to some more amateur observations to confirm the visibility in a 16" class scope so we can finally put the lid on this case - that's why I added a number of amateur observers to the cc list. I was out at a dark site last Saturday night (in the Sierra foothills), but thin clouds made going after tough objects impossible. I'll probably be out again next Saturday night and will give it another try. Steve Gottlieb From: Kenneth Drake To: DenJWebb (forwarded to jhibbard) Dennis, As a matter of fact, My son and I observed it about 5 times in both his 8" Dob and my 24 incher. I had mistakenly put its number (IC694) down as being one of the recent supernovae galaxies!! Oops! BTW, 5 very faint stars are involved. I remember commenting to Josh that NGC 3690 seemed to be very low surface brightness whereas the IC galaxy was easy. The MCG galaxy appeared stellar while Arp 296 was obvious. We even saw the MAC to the east but not the one to the north. So, in a way we did manage to take your challenge?? I don't think the MCG galaxy could be part of the merging pair due to it's stellar appearance. Hope that is what you were looking for. Thanks, Kenneth (jhibbard requested clarification): From drako@ix4.ix.netcom.com Sat May 9 15:39 EDT 1998 To: John Hibbard John, As I originally mentioned, this object was on my list to see if I could identify the supernova. I had gotten a note from Dennis at the last minute and added it to the bottom of my TSP "to do" list. His challenge never got done {:=( My first observation was with the 24 inch at 198 power. A bright circular mottled 1' diameter glow hanging off a much, much fainter elongated 1x2' glow. Up in my Dob was northwest hence the term hanging. I assumed I was looking at IC 694 as plotted by MegaStar (the bright 1' object) RA 11 28 31.1 +58 33 12 (2000), so I was concentrating on it looking for stellar things (the supernova). The only thing that appeared stellar was at the nw end of the very faint elongated object which ran nw-se. This stellar object was plotted as MCG+10-17-2a. It remained stellar at 421 power but keep in mind that the seeing on the Prude Ranch upper field is about 3 to 5 arc seconds most times. At this point I wanted Josh to see it so we found it in his 8" Dob. It was readily visible at 70 power so I had him climb eight feet up to see it in the 24 incher. He immediately commented on the "other" galaxy at the left edge of the field (7' field @ 421 power). It turned out to be Arp 296 just 3' away in P.A. 45. It was easy! Later in the week (early Thursday), I looked during better seeing and counted five faint stellar objects involved in and around the nebulous patches. I varified them in Larry's 36 inch f/5. I also nailed the "FAINT" galaxy 2 minutes south of Arp 296. It is an anonamous object plotted as MAC 1128+5833 in MegaStar. It is part of Larry Mitchell's effort to plot the known universe. John, seeing them is more of a game for me since they are very faint and generally small. I did not detect the one just north at RA 11 28 37.1 +58 37 12 plotted as MAC 1128+5837. Hope this helps define for you what I saw. I plan on looking on May 23rd from a site with better seeing but with the fires in Mexico causing so much haze for us here in Texas, the transparency may really stink! Sincerely, Kenneth Drake From jhibbard Sat May 9 22:44:10 1998 To: drako@ix4.ix.netcom.com Kenneth, Thanks for the clarification. Luckily, I kept the finding chart that Dennis sent around and can now see exactly what you are refering to. Basically, the question we are investigating is whether the discoverer of IC 694 (Swift 1893), using a 16" refractor, was identifying the eastern part of the Arp 299 or the galaxy later classified as MCG +10-17-2A (1' to the NW). Most astronomers since 1959 have assumed the former. The UCG first brought up the possibility that it is the latter. It appears that MegaStar has it confused even more, with IC 694 indicating the western half of Arp 299, and refering to the eastern half as NGC 3690. It sound like you were indeed able to locate MCG +10-17-2A in your 24", although it looked stellar. Would you care to comment on whether you think you would have been able to detect this object if it were 0.9mag fainter (ratio of 24" to 16" collecting areas) and *WITHOUT PRIOR KNOWLEDGE of its existence*? These are the main things we are trying to get visual confirmation or even opinions on. If Swift could have detected this object as extended, then it is likely that it is indeed is the proper benificiary of the IC 694 label. Let me know how it goes on May 23rd, and thanks again. -john ================================================================== Dec 2003: NEW EFFORTS FROM AAVSO: ================================================================== Subject: [vance.petriew@saskeds.com: IC 694] Date: Tue, 2 Dec 2003 10:40:37 -0500 From: Aaron Price To: jhibbard@nrao.edu Hi, John. We received our first positive observation of the field and I include it below. Vance is one of our more advanced observers, feel free to contact him directly if you need. Unfortunately he needed to research the field in order to find it in his telescope. He did his best to limit his knowledge of what to expect but I think he knew of the existence of Arp 296 ahead of time. However, he may not have known of its location and size. Also, he has a 20" dob. So this isn't a perfect experiment for you but at least a start. I have many other amateurs interested but the late rise of the field made it hard. Now that it rises earlier I think observations should start coming in. I'm going to send a reminder to those observers who expressed interest. I'll let you know as soon as they do. Clear skies, Aaron ----- Forwarded message from "Petriew, Vance" ----- X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 Subject: IC 694 Date: Wed, 19 Nov 2003 16:42:39 -0600 X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: IC 694 Thread-Index: AcOu7bZbnMuSG5zkTMGM/bIgpUF3Pw== From: "Petriew, Vance" To: "Aaron Price" X-MIME-Autoconverted: from quoted-printable to 8bit by mira.aavso.org id hAJMgaT03860 X-Spam-Status: No, hits=0.8 required=5.0 tests=SPAM_PHRASE_00_01 version=2.43-cvs X-Spam-Level: X-Keywords: X-UID: 21 Hi Aaron, Here's my observation of IC 694 and the two neighboring galaxies. I didn't look up anything for these except the name, magnitude and size from my planetarium program. It does look pretty neat in the eyepiece but unfortunately, the viewing wasn't very good. It should be directly overhead in March/April. I hope this works for you. I'm very interested in checking out a DSS image as soon as you'll let me :o) Vance November 19th, 2003 Conditions: Some cirrus clouds and ice crystals. No moon. The wind was about 10 km/h with gusts to 30 km/h. The temperature was -8 degrees Celsius and about -15 degrees with the windchill. Limiting magnitude was around 6.0 Andromeda. Transparency was fair. Seeing was fair. IC 694, NGC 3690, Arp 296 12:00 AM CST (6:00 AM UT) Magnitude 12.1 Size 1.1' x 0.9' I was asked by Aaron Price of the AAVSO to take a look at this galaxy sometime without looking up anything about it. The seeing was pretty poor but the bright, large, stellar nucleus was easily seen at 300x. I'd like to see this under better conditions and higher magnification since it was likely the mushy air that made me think that there might be more than one bright nucleus. The galactic disk looked round in the eyepiece and fairly diffuse. The companion galaxy, NGC 3690, was oval in shape with a faint nucleus in the middle. The disk of this galaxy appeared more dense than IC 694 and had more of a defined edge to the disk. Between the two galaxies was a dark lane that seemed to follow the curvature of IC 694 suggesting that IC 694 is likely in front of NGC 3690. Together, the two galaxies reminded me of a Bubble bee with IC 694 being the head and NGC 3690 being the body. The faint galaxy, ARP 296 (PGC 35345) was also barely visible as a faint oval smudge. ----- End forwarded message ----- -- Aaron Price (PAH), Technical Assistant, Technology American Association of Variable Star Observers http://www.aavso.org ==================================================================