Subject: Re: [sloan-25mlog 5919] 2.5m obslog 20220305 (SJD 59644) From: Ryan Wagner Date: Wed, 9 Mar 2022 10:25:06 -0700 --Apple-Mail=_3B735353-B1AE-4A8A-9479-B88A3C598A1D Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 I found a webpage that discusses how to adjust the gain: http://users.apo.nmsu.edu/~sdssobserver/irscAlignAdjust.html = It says the following about adjusting the gain. Note, the webpages = mentioned in the entry are no longer available. SKY-LEVEL AND GAIN ADJUSTMENTS:=20 The final tasks needed after replacing the IRSC's CCD camera was = setting sky- level and gain controls. These pots are contained in the small grey = plastic box,=20 which is located on top of the CCD camera's mount housing (see top_left = photo). =20 You will need to remove four screws and the top cover of this box to = access these=20 controls. After removing the cover, you will notice that the box also = contains three=20 toggle switches. All of the switches and controls are labeled according = to their=20 function. =20 As a starting point, I first made a rough setting of the sky-level = control by=20 monitoring the sky-level plot on the IRSC web page, viz., = http://irsc.apo.nmsu.edu =20 I determined a normal sky-level setting by looking at the values of = archived IRSC=20 images, which were found via a link on the IRSC web page. After the = sky-level was=20 tweaked, I looked at the sky-level plot to monitor the outcome. When I = had the sky- level near the value of the archived images, I moved on to the gain = adjustment.=20 The gain adjustment is MUCH more difficult. In fact, you will need = to do a VERY=20 time consuming IRAF reduction of many IRSC images before the gain will = be properly=20 set. To determine the gain via calib data capture and IRAF reduction, = you will need=20 to use the instructions at my two web pages:=20 http://users.apo.nmsu.edu/~hjbrew/irscCalibData.html http://users.apo.nmsu.edu/~hjbrew/irafReduction.html Nevertheless, a preliminary gain setting is found by doing a visual = inspection=20 of the IRSC images located at the IRSC web page, as well as by = monitoring the sigma (or=20 standard deviation) value located in the top left of the IRSC images. = This value is=20 normally about 5.0 on a good photometric night. So, you will need to = make an educated=20 guess of the gain's setting via the gain pot. FYI, the IRSC system = usually takes about=20 15-minutes to recover a normal image after gain adjustments are made.=20 Next, you will need to do an IRSC data capture and an IRAF = reduction, as explained=20 in my two procedural pages above, to determine the true gain of the = system. An acceptable=20 setting for the gain is 600 (+/- 100) as determined by IRAF. If your = gain-setting guess was=20 wrong, you will need to slightly change the gain-control setting and = collect/reduce more=20 IRSC data until the gain of the system is within spec. Since gain = adjustments affect the=20 sky-level setting (and vise versa), one may need to tweak the sky-level = pot after getting=20 close to a proper gain setting. Looking at the last video from the IRSC I see what the gain issue seen = is. http://users.apo.nmsu.edu/~jwhueh/CloudCamera/latest.mp4 = Probably something that is done during the evening/night and not = something to do during the day? Thanks, Ryan > On Mar 7, 2022, at 16:06, Bill Ketzeback = wrote: >=20 > Negative. I haven=E2=80=99t touched it for the past 2 cameras. Gain = adjustments have been James or a 2.5m observer. Ed has never been = involved. Check with Kaike. >=20 > Bill >=20 > Sent from my iPhone >=20 >> On Mar 7, 2022, at 3:55 PM, Ryan Wagner wrote: >>=20 >> =EF=BB=BFI believe the cloud camera is maintained by Ed and Bill K. I = have CC=E2=80=99d them.=20 >>=20 >> Thank you for pointing this out. >>=20 >> Ryan >>=20 >>> On Mar 6, 2022, at 05:25, asimmons@apo.nmsu.edu = wrote: >>>=20 >>> ---- Engineering Issues ---- >>>=20 >>> The IR cloud camera gain has really become poor. Does anybody know = who is in charge of calibrations nowadays? >>=20 --Apple-Mail=_3B735353-B1AE-4A8A-9479-B88A3C598A1D Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 I = found a webpage that discusses how to adjust the gain:http://users.apo.nmsu.edu/~sdssobserver/irscAlignAdjust.htmlIt says the following about adjusting the gain. = Note, the webpages mentioned in the entry are no longer = available.SKY-LEVEL = AND GAIN ADJUSTMENTS: The final tasks needed after replacing the IRSC's CCD camera was = setting sky- level and gain controls. These pots are contained in the small grey = plastic box,=20 which is located on top of the CCD camera's mount housing (see top_left = photo). =20 You will need to remove four screws and the top cover of this box to = access these=20 controls. After removing the cover, you will notice that the box also = contains three=20 toggle switches. All of the switches and controls are labeled according = to their=20 function. =20 As a starting point, I first made a rough setting of the sky-level = control by=20 monitoring the sky-level plot on the IRSC web page, viz., http://irsc.apo.nmsu.edu = =20 I determined a normal sky-level setting by looking at the values of = archived IRSC=20 images, which were found via a link on the IRSC web page. After the = sky-level was=20 tweaked, I looked at the sky-level plot to monitor the outcome. When I = had the sky- level near the value of the archived images, I moved on to the gain = adjustment.=20 The gain adjustment is MUCH more difficult. In fact, you will need = to do a VERY=20 time consuming IRAF reduction of many IRSC images before the gain will = be properly=20 set. To determine the gain via calib data capture and IRAF reduction, = you will need=20 to use the instructions at my two web pages:=20 http://users.apo.nmsu.edu/~hjbrew/irscCalibData.html http://users.apo.nmsu.edu/~hjbrew/irafReduction.html Nevertheless, a preliminary gain setting is found by doing a visual = inspection=20 of the IRSC images located at the IRSC web page, as well as by = monitoring the sigma (or=20 standard deviation) value located in the top left of the IRSC images. = This value is=20 normally about 5.0 on a good photometric night. So, you will need to = make an educated=20 guess of the gain's setting via the gain pot. FYI, the IRSC system = usually takes about=20 15-minutes to recover a normal image after gain adjustments are made.=20 Next, you will need to do an IRSC data capture and an IRAF = reduction, as explained=20 in my two procedural pages above, to determine the true gain of the = system. An acceptable=20 setting for the gain is 600 (+/- 100) as determined by IRAF. If your = gain-setting guess was=20 wrong, you will need to slightly change the gain-control setting and = collect/reduce more=20 IRSC data until the gain of the system is within spec. Since gain = adjustments affect the=20 sky-level setting (and vise versa), one may need to tweak the sky-level = pot after getting=20 close to a proper gain setting.Looking at = the last video from the IRSC I see what the gain issue seen = is.http://users.apo.nmsu.edu/~jwhueh/CloudCamera/latest.mp4Probably = something that is done during the evening/night and not something to do = during the day?Thanks,RyanOn Mar 7, 2022, at 16:06, Bill Ketzeback = wrote:Negative. I haven=E2=80=99t = touched it for the past 2 cameras. Gain adjustments have been James or a = 2.5m observer. Ed has never been involved. Check with Kaike.BillSent from my iPhoneOn Mar 7, 2022, at 3:55 PM, Ryan Wagner wrote:=EF=BB=BFI believe the cloud = camera is maintained by Ed and Bill K. I have CC=E2=80=99d = them. Thank = you for pointing this out.RyanOn Mar 6, 2022, at 05:25, asimmons@apo.nmsu.edu= wrote:---- = Engineering Issues ----The IR cloud camera gain has really become poor. Does anybody = know who is in charge of calibrations = nowadays?= --Apple-Mail=_3B735353-B1AE-4A8A-9479-B88A3C598A1D--