This is a multi-part message in MIME format. ------=_NextPart_000_005F_01C2C3C6.7AD14070 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable My apologies if you receive this notice more than once. If you have = already received a message with the subject line above, then you can = ignore this one. This is to inform the general population of DIS users that we have = completed successful installation of the new BLUE camera optics. Details = of initial measurements of the spectrograph are given below. We are = currently planning to install the new RED camera optics sometime in = February. At that time we will also make another effort to eliminate = the pesky 120 Hz noise spikes that are present in the red camera = electronics. Peter Doherty has made us a new preamp card which will be = installed in the red dewar when it gets opened for the optics = installation. With the installation of the red optics DIS will = officially become DIS III and we will have completed all of the = currently agreed upon upgrades. Note that discussions are still = underway on whether or not we will attempt to fix the UV (i.e. below = 3800 A) throughput problems on DIS (and thus present you with a DIS IV = sometime in the next 12 months). With this latest work on the = spectrograph it is possible that some of the UV response has been = improved, but we currently have no measurements to support this. It = will be a high priority to obtain the appropriate on-sky measurements of = the DIS UV throughput during the next scheduled engineering run. Using the 0.9" slit and the high resolution blue grating, we have = obtained slit images of about 2.3 pixels width. A dispersion of 0.62 = A/pix was measured for this grating near 4400 A This line width is = therefore equivalent to a spectral width of 1.43 A. Scaling suggests = that the imaging scale is now 0.42"/pix. This parameter will not be = measured directly until we have on-sky measurements from DIS. This = should happen sometime this weekend. These values are close to the expected values. Note that for a slit of = 0.9" width with perfect optics one might expect to see slit widths of = 2.14 pixels. We were in fact able to see slit width images of this = size, but not simultaneously across the entire FOV. Some improvements = in the focus might be made with a day or two of effort, but we didn't = think it was worth that much fine tuning. It would be best to wait to = see what the temperature variations do to us before spending this much = effort on the focus. We measured about a 2% variation of the dispersion from the center of = the chip to the edge, with decreasing dispersions near the red end of = the spectrum. We also measured a slight "bow" to the shape of the = spectral lines, similar to that which was present in the old optics. = From the center of the spectrum to the top or bottom there is about a 2 = pixel difference in the column position of the slit image centroid. = Users will note that there is a slight tilt in the spectrum which is the = result of a comprimse between spatial and spectral purity. The top of = the slit image on the left (blue side) of the spectrum is 5 pixels below = the top of the slit image on the right side of the spectrum. This tilt = is unaviodable if you wish to minimize the effect of the "bowing" of the = spectral lines. We have chosen to align the spectrum in such a way as = to maximize the spectra purity of each line rather than maximizing the = spatial purity along the line. In any case, these are small effects, = but we want the users to be aware of them. Measurements of the low and medium resolution gratings have now been = done through the efforts of John Barentine. He found dispersions of = 2.42 and 1.23 A/pix. These values are within 2.5% of what one would = have expected based on scaling of the old DIS dispersions to match the = new high resolution grating measurements. Plots of his dispersion = measurements can be found at: http://galileo.apo.nmsu.edu/~jcb/dis_blue_dispersion.gif The spectrum is now nicely centered on the chip and the vignetting = appears to be small. A few preliminary data points indicate that the = vignetting is somewhere between 10% and 20% near the left and right = edges of the chip. Vignetting along the spatial dimension should be = much smaller than this. Further efforts are still needed to = characterize the vignetting. =20 The chip is now nicely matched to the full 6x4 arcminute FOV of the spectrograph. However, users should note that the current suite of = slits in use are only 5 arcminutes in length. I would highly encourage the = site to quickly obtain a set of slits that make use of the complete FOV = of the spectrograph. (Alan Uomoto, are you available to help us out = here?) In short, with the caveats that come with having only preliminary data,=20 the new blue camera does everything that we had hoped it would! My = thanks once again go to Peter Doherty, Mark Klaene, Craig Loomis, Jon = Davies, Dave Woods, and John Barentine for their dedicated and wonderful = help with getting this work done. See you all in a month (except = Peter...I'll see him in about 10 minutes)! Jeff Morgan UW Astronomy Box 351580 Seattle, WA 98195 (206) 543-6182 ------=_NextPart_000_005F_01C2C3C6.7AD14070 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>My apologies if you receive this notice more than once. If = you have=20 already received a message with the subject line above, then you can = ignore this=20 one.</DIV> <DIV> </DIV> <DIV> <DIV>This is to inform the general population of DIS users that we have=20 completed successful installation of the new BLUE camera optics. Details = of=20 initial measurements of the spectrograph are given below. We are = currently=20 planning to install the new RED camera optics sometime in = February. At=20 that time we will also make another effort to eliminate the pesky 120 Hz = noise=20 spikes that are present in the red camera electronics. Peter = Doherty has=20 made us a new preamp card which will be installed in the red dewar = when it=20 gets opened for the optics installation. With the installation of = the red=20 optics DIS will officially become DIS III and we will have completed all = of the=20 currently agreed upon upgrades. Note that discussions are still = underway=20 on whether or not we will attempt to fix the UV (i.e. below 3800 A)=20 throughput problems on DIS (and thus present you with a DIS IV = sometime in=20 the next 12 months). With this latest work on the spectrograph it = is=20 possible that some of the UV response has been improved, but we = currently have=20 no measurements to support this. It will be a high priority to = obtain the=20 appropriate on-sky measurements of the DIS UV throughput during the next = scheduled engineering run.</DIV> <DIV> </DIV> <DIV>Using the 0.9" slit and the high resolution blue grating, we = have=20 obtained slit images of about 2.3 pixels width. A dispersion of = 0.62=20 A/pix was measured for this grating near 4400 A This = line width=20 is therefore equivalent to a spectral width of 1.43 A. Scaling = suggests=20 that the imaging scale is now 0.42"/pix. This parameter will not = be=20 measured directly until we have on-sky measurements from DIS. This = should=20 happen sometime this weekend.</DIV> <DIV> </DIV> <DIV>These values are close to the expected values. Note that for = a slit=20 of 0.9" width with perfect optics one might expect to see slit widths of = 2.14=20 pixels. We were in fact able to see slit width images of this = size, but=20 not simultaneously across the entire FOV. Some improvements in the = focus=20 might be made with a day or two of effort, but we didn't think it was = worth that=20 much fine tuning. It would be best to wait to see what the = temperature=20 variations do to us before spending this much effort on the focus.</DIV> <DIV><BR> We measured about a 2% variation of the dispersion from = the=20 center of the chip to the edge, with decreasing dispersions near the red = end of=20 the spectrum. We also measured a slight "bow" to the shape of the = spectral=20 lines, similar to that which was present in the old optics. From = the=20 center of the spectrum to the top or bottom there is about a 2=20 pixel difference in the column position of the slit image = centroid. =20 Users will note that there is a slight tilt in the spectrum which is the = result=20 of a comprimse between spatial and spectral purity. The = top of=20 the slit image on the left (blue side) of the = spectrum is 5=20 pixels below the top of the slit image on the right side of the = spectrum. =20 This tilt is unaviodable if you wish to minimize the effect of the = "bowing"=20 of the spectral lines. We have chosen to align the spectrum in = such a way=20 as to maximize the spectra purity of each line rather than maximizing = the=20 spatial purity along the line. In any case, these are small = effects,=20 but we want the users to be aware of them.<BR><BR>Measurements of the = low and=20 medium resolution gratings have now been done through the efforts of = John=20 Barentine. He found dispersions of 2.42 and 1.23 = A/pix. These=20 values are within 2.5% of what one would have expected based on scaling = of the=20 old DIS dispersions to match the new high resolution grating = measurements. =20 Plots of his dispersion measurements can be found at:</DIV> <DIV><A=20 href=3D"http://galileo.apo.nmsu.edu/~jcb/dis_blue_dispersion.gif">http://= galileo.apo.nmsu.edu/~jcb/dis_blue_dispersion.gif</A><BR><BR>The=20 spectrum is now nicely centered on the chip and the vignetting appears = to be=20 small. A few preliminary data points indicate that the vignetting = is=20 somewhere between 10% and 20% near the left and right edges of the = chip. =20 Vignetting along the spatial dimension should be much smaller than=20 this. Further efforts are still needed to characterize the=20 vignetting. <BR><BR>The chip is now nicely matched to the full 6x4 = arcminute FOV of the<BR>spectrograph. However, users should note = that the=20 current suite of slits<BR>in use are only 5 arcminutes in length. = I would=20 highly encourage the site to quickly obtain a set of slits that make use = of the=20 complete FOV of the spectrograph. (Alan Uomoto, are you available to = help us out=20 here?)<BR><BR>In short, with the caveats that come with having only = preliminary=20 data, <BR>the new blue camera does everything that we had hoped it = would! =20 My thanks once again go to Peter Doherty, Mark Klaene, Craig Loomis, Jon = Davies,=20 Dave Woods, and John Barentine for their dedicated and wonderful = help with=20 getting this work done. See you all in a month (except = Peter...I'll see=20 him in about 10 minutes)!<BR></DIV></DIV> <DIV> </DIV> <DIV>Jeff Morgan<BR>UW Astronomy<BR>Box 351580<BR>Seattle, WA = 98195 (206)=20 543-6182</DIV></BODY></HTML> ------=_NextPart_000_005F_01C2C3C6.7AD14070-- APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 653 in the apo35-general archive. You can find APO the archive on http://www.astro.princeton.edu/APO/apo35-general/INDEX.html APO To join/leave the list, send mail to apo35-request@astro.princeton.edu APO To post a message, mail it to apo35-general@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO