This is a multi-part message in MIME format. ------=_NextPart_000_01AC_01C2A770.D3071E30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable We would like to inform the general community of DIS users that the = upgrade of the camera optics is currently scheduled to take place during = the week starting 13 Jan 2003. Current DIS users should be aware that this upgrade will have the = following effects on the data format. 1) The pixel scales will change from the current value of ~0.54"/pixel = (both red and blue sides) to 0.40"/pixel for the red camera and to = 0.42"/pixel for the blue camera. Note that the new optics will NOT = change the total field of views for either side of the spectrograph. = For the imaging mode you will still have a 6'x4' FOV and for the = spectroscopic mode you will still have a 6' long slit. With the new = camera optics, spectra will be spread across the entire length and width = of the detectors. 2) The vignetting of the current cameras will be eliminated. This = vignetting has no impact on the imaging mode, but seriously impairs = spectroscopic measurements. The new cameras will afford the following = dispersions and bandpasses: Red Camera Dispersion Bandpass Low dispersion grating: 330.83 A/mm 5650* A Med. dispersion grating: 159.82 4100=20 High dispersion grating: 51.46 1370 Blue Camera Low dispersion grating: 172.46 1900* Med. dispersion grating: 83.66 1900* High dispersion grating: 38.60 1010 =20 *These bandpasses are determined by the atmospheric and dichroic cutoffs = rather than by the detector. The new blue camera optics MAY have an impact on the throughput of = the bluest wavelengths accessible with DIS. The current blue camera = optics show transmission curves which are above 90% at wavelengths = greater than 3500 A. Thus, it is possible that the blue response of the = spectrograph will be considerably enhanced between 3500 and 4000 A. = However, users should be aware that even after this upgrade there will = be one optical element near the front of the spectrograph which will = still have the original multi-layer coating. If the attenuation of this = single surface at these wavelengths is strong enough, then the new = optics will not help the blue throughput problem. This problem will = then have to be addressed at a later time. Also note that as of a few weeks ago, the new parallel read-out boards = were successfully installed in the spectrograph. Both cameras now = read-out simultaneously without noise problems. This results in a = substantial savings of time for most observations. =20 We all have Peter Doherty and Craig Loomis to thank for that work. =20 At the same time that the new optics are installed we will also be = installing a new pre-amp board into the red camera in an effort to = eliminate the 120 Hz noise spikes that are currently present in that = detector. We thank you for your patience. Hopefully by the last week in January = we will have good news to report on the DIS optics upgrade! Jeff Morgan UW Astronomy Box 351580 Seattle, WA 98195 (206) 543-6182 ------=_NextPart_000_01AC_01C2A770.D3071E30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML 6.00.2800.1106" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV>We would like to inform the general community of DIS users that the = upgrade=20 of the camera optics is currently scheduled to take place during the = week=20 starting 13 Jan 2003.</DIV> <DIV> </DIV> <DIV>Current DIS users should be aware that this upgrade will have the = following=20 effects on the data format.</DIV> <DIV> </DIV> <DIV>1) The pixel scales will change from the current value of=20 ~0.54"/pixel (both red and blue sides) to 0.40"/pixel for the red = camera=20 and to 0.42"/pixel for the blue camera. Note that the new optics = will NOT=20 change the total field of views for either side of the = spectrograph. For=20 the imaging mode you will still have a 6'x4' FOV and for the = spectroscopic mode=20 you will still have a 6' long slit. With the new camera optics, = spectra=20 will be spread across the entire length and width of the = detectors.</DIV> <DIV> </DIV> <DIV>2) The vignetting of the current cameras will be = eliminated. =20 This vignetting has no impact on the imaging mode, but seriously impairs = spectroscopic measurements. The new cameras will afford the = following=20 dispersions and bandpasses:</DIV> <DIV> </DIV> <DIV><STRONG>Red Camera = =20 =20 Dispersion Bandpass</STRONG></DIV> <DIV><STRONG>Low dispersion grating:</STRONG> 330.83=20 A/mm 5650* A</DIV> <DIV><STRONG>Med. dispersion grating: =20 </STRONG>159.82 =20 4100 </DIV> <DIV><STRONG>High dispersion grating: =20 </STRONG>51.46  = ; 1370</DIV> <DIV> </DIV> <DIV><STRONG>Blue Camera</STRONG></DIV> <DIV><STRONG>Low dispersion grating: =20 </STRONG>172.46 =20 1900*</DIV> <DIV><STRONG>Med. dispersion grating: =20 </STRONG>83.66  = ; 1900*</DIV> <DIV><STRONG>High dispersion grating: =20 </STRONG>38.60  = ; 1010 </DIV> <DIV> </DIV> <DIV>*These bandpasses are determined by the atmospheric and dichroic = cutoffs=20 rather than by the detector.</DIV> <DIV> </DIV> <DIV> The new blue camera optics MAY have an impact on = the=20 throughput of the bluest wavelengths accessible with DIS. The = current=20 blue camera optics show transmission curves which are above 90%=20 at wavelengths greater than 3500 A. Thus, it is possible = that=20 the blue response of the spectrograph will be considerably enhanced = between=20 3500 and 4000 A. However, users should be aware that even after = this=20 upgrade there will be one optical element near the front of the=20 spectrograph which will still have the original multi-layer = coating. If=20 the attenuation of this single surface at these wavelengths is strong = enough,=20 then the new optics will not help the blue throughput problem. = This=20 problem will then have to be addressed at a later time.</DIV> <DIV> </DIV> <DIV>Also note that as of a few weeks ago, the new parallel read-out = boards were=20 successfully installed in the spectrograph. Both cameras now = read-out=20 simultaneously without noise problems. This results in a = substantial=20 savings of time for most observations. </DIV> <DIV> </DIV> <DIV>We all have Peter Doherty and Craig Loomis to thank for that = work. =20 </DIV> <DIV> </DIV> <DIV>At the same time that the new optics are installed we will also be=20 installing a new pre-amp board into the red camera in an effort to = eliminate the=20 120 Hz noise spikes that are currently present in that detector.</DIV> <DIV> </DIV> <DIV>We thank you for your patience. Hopefully by the last week in = January=20 we will have good news to report on the DIS optics upgrade!</DIV> <DIV> </DIV> <DIV>Jeff Morgan</DIV> <DIV>UW Astronomy<BR>Box 351580<BR>Seattle, WA 98195 (206)=20 543-6182</DIV></BODY></HTML> ------=_NextPart_000_01AC_01C2A770.D3071E30-- APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 642 in the apo35-general archive. 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