The current specifications for the solar filter are listed in the (unapproved) Front End Sub-System Technical Specification, which is document 99 in the Document Approval Request queue in almaedm with a URL of: http://almaedm.tuc.nrao.edu/forums/alma/dispatch.cgi/docapproval/docProfile/100636/d20040408155506/No/t100636.htm 4.2.5. Solar Filter A solar filter shall be provided to allow solar observations. It shall be possible to insert the filter into the RF beam of any of the ALMA bands under remote control. [FEND-40.00.00.00-00200-00 / T] 4.2.5.1. Infrared attenuation [FEND-40.00.00.00-00200-00 / T] The solar filter shall attenuate the incident infrared radiation by at least 20 dB. 4.2.5.2. RF attenuation [FEND-40.00.00.00-00205-00 / T] The solar filter shall attenuate the RF signal by 13 ±3 dB.