Subject: Re: [sloan-25mlog 3498] 2.5m obslog 20170509 (SJD 57883)
From: John Downey
Date: Wed, 10 May 2017 08:25:47 -0600
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I think last night's circumstances show the need for a humidity/weather =
forecast standard in considering whether or not to open in dusty =
conditions.  Dan L pointed out this morning that it may not be possible =
to clean the mirror today, if the dew point depression never rises above =
6 C, as fogging will likely make things worse over the longer term.  =
Condensation on the mirror is likely to "cement" dust to the aluminum =
surface.
Since we were already close to 30k when I was here for the amplifier =
problems, and accumulations had slowed considerably, I ok'd staying open =
past 30k because I wanted to see if the amp kept behaving through the =
night - and observing tests that far better than we can during the day.  =
I'll admit though, I too forgot about the implications of today's =
weather forecast.
Please note, everyone, that the discussion following is not intended to =
criticize Audrey's call to open and observe, as it followed the =
standards as outlined.  Judgement varies, so I don't want all this to be =
interpreted as blame, rather as a rationale for improving the written =
procedure to prevent problems later.
I would suggest that the opening procedure be modified to take into =
account current humidity (above 30%?), weather forecast both for =
overnight wind (proxy for expected dust) and precip the following day =
(could prevent cleaning), and observing requirements - double length =
exposure?  Dither or not? Seeing conditions, etc.
Looking over the observing procedures for weather closing & opening, I =
don't see a clear mention of which of the two dust counts the hourly =
standard refers to, or any consideration of the humidity at the time of =
opening - humidity only seems to be considered in the change for =
integrated counts over the night.
Looking at the weather log, I think the procedure should probably be =
clarified to prevent opening under last night's conditions:
2017-05-10 02:21:51.626Z actor            20 apoCmd.py:125 0 20 =
pressure=3D21.352; windd=3D273.8; winds=3D4.4; gustd=3D219.0; gusts=3D7.2;=
 airtemp=3D7.2; dewpoint=3D-2.7; dpErr=3DP; humidity=3D49.2; =
dusta=3D41055; dustb=3D4744; dustc=3D2111; dustd=3D636; encl25m=3D0; =
truss25m=3D8.67; airTempPT=3D7.2; dpTempPT=3D-1.9; humidPT=3D52.5; =
irscmean=3D346; irscsd=3D52.89
2017-05-10 02:21:51.673Z cmdr             10 CmdrConnection.py:53 read: =
.apo 39192 apo : pressure=3D21.352; windd=3D273.8; winds=3D4.4; =
gustd=3D219.0; gusts=3D7.2; airtemp=3D7.2; dewpoint=3D-2.7; dpErr=3DP; =
humidity=3D49.2; dusta=3D41055; dustb=3D4744; dustc=3D2111; dustd=3D636; =
encl25m=3D0; truss25m=3D8.67; airTempPT=3D7.2; dpTempPT=3D-1.9; =
humidPT=3D52.5; irscmean=3D346; irscsd=3D52.89
2017-05-10 02:26:51.620Z actor            20 apoCmd.py:125 2 20 =
pressure=3D21.352; windd=3D265.0; winds=3D5.1; gustd=3D292.8; gusts=3D8.9;=
 airtemp=3D7.4; dewpoint=3D-2.6; dpErr=3DP; humidity=3D49.0; =
dusta=3D42268; dustb=3D5562; dustc=3D2156; dustd=3D689; windd25m=3D326.4; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D8.49; airTempPT=3D7.4; =
dpTempPT=3D-1.5; humidPT=3D53.2; irscmean=3D378; irscsd=3D99.79
2017-05-10 02:26:51.672Z cmdr             10 CmdrConnection.py:53 read: =
.apo 39197 apo : pressure=3D21.352; windd=3D265.0; winds=3D5.1; =
gustd=3D292.8; gusts=3D8.9; airtemp=3D7.4; dewpoint=3D-2.6; dpErr=3DP; =
humidity=3D49.0; dusta=3D42268; dustb=3D5562; dustc=3D2156; dustd=3D689; =
windd25m=3D326.4; winds25m=3D1.3; encl25m=3D16; truss25m=3D8.49; =
airTempPT=3D7.4; dpTempPT=3D-1.5; humidPT=3D53.2; irscmean=3D378; =
irscsd=3D99.79
2017-05-10 02:31:51.641Z actor            20 apoCmd.py:125 0 22 =
pressure=3D21.354; windd=3D264.9; winds=3D4.3; gustd=3D292.8; gusts=3D8.9;=
 airtemp=3D7.0; dewpoint=3D-2.3; dpErr=3DP; humidity=3D51.4; =
dusta=3D42970; dustb=3D6318; dustc=3D2219; dustd=3D766; windd25m=3D351.6; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D8.21; airTempPT=3D7.2; =
dpTempPT=3D-1.3; humidPT=3D54.7; irscmean=3D378; irscsd=3D97.99
2017-05-10 02:31:51.690Z cmdr             10 CmdrConnection.py:53 read: =
.apo 39202 apo : pressure=3D21.354; windd=3D264.9; winds=3D4.3; =
gustd=3D292.8; gusts=3D8.9; airtemp=3D7.0; dewpoint=3D-2.3; dpErr=3DP; =
humidity=3D51.4; dusta=3D42970; dustb=3D6318; dustc=3D2219; dustd=3D766; =
windd25m=3D351.6; winds25m=3D1.3; encl25m=3D16; truss25m=3D8.21; =
airTempPT=3D7.2; dpTempPT=3D-1.3; humidPT=3D54.7; irscmean=3D378; =
irscsd=3D97.99
2017-05-10 02:36:51.618Z actor            20 apoCmd.py:125 0 22 =
pressure=3D21.352; windd=3D295.8; winds=3D4.0; gustd=3D292.8; gusts=3D8.9;=
 airtemp=3D6.9; dewpoint=3D-2.2; dpErr=3DP; humidity=3D52.2; =
dusta=3D43243; dustb=3D6424; dustc=3D2268; dustd=3D759; windd25m=3D0.7; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D7.93; airTempPT=3D7.0; =
dpTempPT=3D-1.3; humidPT=3D55.4; irscmean=3D381; irscsd=3D96.01
2017-05-10 02:36:51.668Z cmdr             10 CmdrConnection.py:53 read: =
.apo 39207 apo : pressure=3D21.352; windd=3D295.8; winds=3D4.0; =
gustd=3D292.8; gusts=3D8.9; airtemp=3D6.9; dewpoint=3D-2.2; dpErr=3DP; =
humidity=3D52.2; dusta=3D43243; dustb=3D6424; dustc=3D2268; dustd=3D759; =
windd25m=3D0.7; winds25m=3D1.3; encl25m=3D16; truss25m=3D7.93; =
airTempPT=3D7.0; dpTempPT=3D-1.3; humidPT=3D55.4; irscmean=3D381; =
irscsd=3D96.01
2017-05-10 02:41:51.655Z actor            20 apoCmd.py:125 0 22 =
pressure=3D21.355; windd=3D279.0; winds=3D3.9; gustd=3D310.3; gusts=3D8.1;=
 airtemp=3D6.4; dewpoint=3D-1.8; dpErr=3DP; humidity=3D55.4; =
dusta=3D49625; dustb=3D10553; dustc=3D2512; dustd=3D918; windd25m=3D19.3; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D7.55; airTempPT=3D6.8; =
dpTempPT=3D-0.6; humidPT=3D59.0; irscmean=3D347; irscsd=3D86.80
2017-05-10 02:41:51.704Z cmdr             10 CmdrConnection.py:53 read: =
.apo 39212 apo : pressure=3D21.355; windd=3D279.0; winds=3D3.9; =
gustd=3D310.3; gusts=3D8.1; airtemp=3D6.4; dewpoint=3D-1.8; dpErr=3DP; =
humidity=3D55.4; dusta=3D49625; dustb=3D10553; dustc=3D2512; dustd=3D918; =
windd25m=3D19.3; winds25m=3D1.3; encl25m=3D16; truss25m=3D7.55; =
airTempPT=3D6.8; dpTempPT=3D-0.6; humidPT=3D59.0; irscmean=3D347; =
irscsd=3D86.80
2017-05-10 02:46:51.617Z actor            20 apoCmd.py:125 0 22 =
pressure=3D21.355; windd=3D305.0; winds=3D6.2; gustd=3D310.3; gusts=3D8.1;=
 airtemp=3D6.4; dewpoint=3D-1.4; dpErr=3DP; humidity=3D57.5; =
dusta=3D47301; dustb=3D9427; dustc=3D2673; dustd=3D1062; windd25m=3D22.7; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D7.27; airTempPT=3D6.8; =
dpTempPT=3D-0.7; humidPT=3D58.8; irscmean=3D335; irscsd=3D59.10
2017-05-10 02:46:51.669Z cmdr             10 CmdrConnection.py:53 read: =
.apo 39217 apo : pressure=3D21.355; windd=3D305.0; winds=3D6.2; =
gustd=3D310.3; gusts=3D8.1; airtemp=3D6.4; dewpoint=3D-1.4; dpErr=3DP; =
humidity=3D57.5; dusta=3D47301; dustb=3D9427; dustc=3D2673; dustd=3D1062; =
windd25m=3D22.7; winds25m=3D1.3; encl25m=3D16; truss25m=3D7.27; =
airTempPT=3D6.8; dpTempPT=3D-0.7; humidPT=3D58.8; irscmean=3D335; =
irscsd=3D59.10
dusta is 0.3u and dustb is 1.0u -- dustc and dustd are most likely the =
3.5m counts.
Is the standard for 1.0u 30%) and the forecast indicates it will be around =
for a while, then the wise course is to probably cut the micron standard =
in half for opening or even to look at the 0.3u count instead.  Under =
such conditions the seeing is likely to be marginal in any case, so =
waiting a few more hours won't deprive us of any fantastic data.
Kaike and Dmitry can set the actual standards as far as I'm concerned, =
what I've suggested above is just a guess and I can't really offer =
advice on the implications of types of observations (double exposure, =
etc).  I do think a discussion of checking tomorrow's forecast is an =
important bit to add though.
Thanks,
John
>=20
> ---- Observing Summary ----
>=20
> We opened with a small delay because of dust.=20
> - Dust levels are large. We could not observe more than 3 hours for =
the
> accumulated dust. PLEASE CLEAN THE MIRRORS.=20
>=20
> Delayed ventilating. Lots of clouds/radar. Huge dust cloud outside.
>=20
>=20
> Weather still poor, but dust starting to drop.
>=20
>=20
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I think last night's circumstances show the need for a =
humidity/weather forecast standard in considering whether or not to open =
in dusty conditions.  Dan L pointed out this morning that it may =
not be possible to clean the mirror today, if the dew point depression =
never rises above 6 C, as fogging will likely make things worse over the =
longer term.  Condensation on the mirror is likely to "cement" dust =
to the aluminum surface.Since we =
were already close to 30k when I was here for the amplifier problems, =
and accumulations had slowed considerably, I ok'd staying open past 30k =
because I wanted to see if the amp kept behaving through the night - and =
observing tests that far better than we can during the day.  I'll =
admit though, I too forgot about the implications of today's weather =
forecast.Please note, =
everyone, that the discussion following is not intended to criticize =
Audrey's call to open and observe, as it followed the standards as =
outlined.  Judgement varies, so I don't want all this to be =
interpreted as blame, rather as a rationale for improving the written =
procedure to prevent problems later.I would suggest that the opening procedure =
be modified to take into account current humidity (above 30%?), weather =
forecast both for overnight wind (proxy for expected dust) and precip =
the following day (could prevent cleaning), and observing requirements - =
double length exposure?  Dither or not? Seeing conditions, =
etc.Looking over the observing =
procedures for weather closing & opening, I don't see a clear =
mention of which of the two dust counts the hourly standard refers to, =
or any consideration of the humidity at the time of opening - humidity =
only seems to be considered in the change for integrated counts over the =
night.Looking at the weather log, I =
think the procedure should probably be clarified to prevent opening =
under last night's conditions:2017-05-10 02:21:51.626Z actor        =
    20 apoCmd.py:125 0 20 pressure=3D21.352; windd=3D273.8; =
winds=3D4.4; gustd=3D219.0; gusts=3D7.2; airtemp=3D7.2; dewpoint=3D-2.7; =
dpErr=3DP; humidity=3D49.2; =
dusta=3D41055; dustb=3D4744; =
dustc=3D2111; dustd=3D636; encl25m=3D0; truss25m=3D8.67; airTempPT=3D7.2; =
dpTempPT=3D-1.9; humidPT=3D52.5; irscmean=3D346; irscsd=3D52.892017-05-10 02:21:51.673Z cmdr         =
    10 CmdrConnection.py:53 read: .apo 39192 apo : =
pressure=3D21.352; windd=3D273.8; winds=3D4.4; gustd=3D219.0; gusts=3D7.2;=
 airtemp=3D7.2; dewpoint=3D-2.7; dpErr=3DP; humidity=3D49.2; =
dusta=3D41055; dustb=3D4744; dustc=3D2111; dustd=3D636; encl25m=3D0; =
truss25m=3D8.67; airTempPT=3D7.2; dpTempPT=3D-1.9; humidPT=3D52.5; =
irscmean=3D346; irscsd=3D52.892017-05-10 =
02:26:51.620Z actor            20 =
apoCmd.py:125 2 20 pressure=3D21.352; windd=3D265.0; winds=3D5.1; =
gustd=3D292.8; gusts=3D8.9; airtemp=3D7.4; dewpoint=3D-2.6; dpErr=3DP; =
humidity=3D49.0; dusta=3D42268; =
dustb=3D5562; dustc=3D2156; dustd=3D689; windd25m=3D326.4; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D8.49; airTempPT=3D7.4; =
dpTempPT=3D-1.5; humidPT=3D53.2; irscmean=3D378; irscsd=3D99.792017-05-10 02:26:51.672Z cmdr         =
    10 CmdrConnection.py:53 read: .apo 39197 apo : =
pressure=3D21.352; windd=3D265.0; winds=3D5.1; gustd=3D292.8; gusts=3D8.9;=
 airtemp=3D7.4; dewpoint=3D-2.6; dpErr=3DP; humidity=3D49.0; =
dusta=3D42268; dustb=3D5562; dustc=3D2156; dustd=3D689; windd25m=3D326.4; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D8.49; airTempPT=3D7.4; =
dpTempPT=3D-1.5; humidPT=3D53.2; irscmean=3D378; irscsd=3D99.792017-05-10 02:31:51.641Z actor        =
    20 apoCmd.py:125 0 22 pressure=3D21.354; windd=3D264.9; =
winds=3D4.3; gustd=3D292.8; gusts=3D8.9; airtemp=3D7.0; dewpoint=3D-2.3; =
dpErr=3DP; humidity=3D51.4; =
dusta=3D42970; dustb=3D6318; dustc=3D2219; dustd=3D766; =
windd25m=3D351.6; winds25m=3D1.3; encl25m=3D16; truss25m=3D8.21; =
airTempPT=3D7.2; dpTempPT=3D-1.3; humidPT=3D54.7; irscmean=3D378; =
irscsd=3D97.992017-05-10 02:31:51.690Z cmdr   =
          10 CmdrConnection.py:53 read: .apo =
39202 apo : pressure=3D21.354; windd=3D264.9; winds=3D4.3; gustd=3D292.8; =
gusts=3D8.9; airtemp=3D7.0; dewpoint=3D-2.3; dpErr=3DP; humidity=3D51.4; =
dusta=3D42970; dustb=3D6318; dustc=3D2219; dustd=3D766; windd25m=3D351.6; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D8.21; airTempPT=3D7.2; =
dpTempPT=3D-1.3; humidPT=3D54.7; irscmean=3D378; irscsd=3D97.992017-05-10 02:36:51.618Z actor        =
    20 apoCmd.py:125 0 22 pressure=3D21.352; windd=3D295.8; =
winds=3D4.0; gustd=3D292.8; gusts=3D8.9; airtemp=3D6.9; dewpoint=3D-2.2; =
dpErr=3DP; humidity=3D52.2; =
dusta=3D43243; dustb=3D6424; dustc=3D2268; dustd=3D759; =
windd25m=3D0.7; winds25m=3D1.3; encl25m=3D16; truss25m=3D7.93; =
airTempPT=3D7.0; dpTempPT=3D-1.3; humidPT=3D55.4; irscmean=3D381; =
irscsd=3D96.012017-05-10 02:36:51.668Z cmdr   =
          10 CmdrConnection.py:53 read: .apo =
39207 apo : pressure=3D21.352; windd=3D295.8; winds=3D4.0; gustd=3D292.8; =
gusts=3D8.9; airtemp=3D6.9; dewpoint=3D-2.2; dpErr=3DP; humidity=3D52.2; =
dusta=3D43243; dustb=3D6424; dustc=3D2268; dustd=3D759; windd25m=3D0.7; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D7.93; airTempPT=3D7.0; =
dpTempPT=3D-1.3; humidPT=3D55.4; irscmean=3D381; irscsd=3D96.012017-05-10 02:41:51.655Z actor        =
    20 apoCmd.py:125 0 22 pressure=3D21.355; windd=3D279.0; =
winds=3D3.9; gustd=3D310.3; gusts=3D8.1; airtemp=3D6.4; dewpoint=3D-1.8; =
dpErr=3DP; humidity=3D55.4; =
dusta=3D49625; dustb=3D10553; dustc=3D2512; dustd=3D918; =
windd25m=3D19.3; winds25m=3D1.3; encl25m=3D16; truss25m=3D7.55; =
airTempPT=3D6.8; dpTempPT=3D-0.6; humidPT=3D59.0; irscmean=3D347; =
irscsd=3D86.802017-05-10 02:41:51.704Z cmdr   =
          10 CmdrConnection.py:53 read: .apo =
39212 apo : pressure=3D21.355; windd=3D279.0; winds=3D3.9; gustd=3D310.3; =
gusts=3D8.1; airtemp=3D6.4; dewpoint=3D-1.8; dpErr=3DP; humidity=3D55.4; =
dusta=3D49625; dustb=3D10553; dustc=3D2512; dustd=3D918; windd25m=3D19.3; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D7.55; airTempPT=3D6.8; =
dpTempPT=3D-0.6; humidPT=3D59.0; irscmean=3D347; irscsd=3D86.802017-05-10 02:46:51.617Z actor        =
    20 apoCmd.py:125 0 22 pressure=3D21.355; windd=3D305.0; =
winds=3D6.2; gustd=3D310.3; gusts=3D8.1; airtemp=3D6.4; dewpoint=3D-1.4; =
dpErr=3DP; humidity=3D57.5; =
dusta=3D47301; dustb=3D9427; dustc=3D2673; dustd=3D1062; =
windd25m=3D22.7; winds25m=3D1.3; encl25m=3D16; truss25m=3D7.27; =
airTempPT=3D6.8; dpTempPT=3D-0.7; humidPT=3D58.8; irscmean=3D335; =
irscsd=3D59.102017-05-10 02:46:51.669Z cmdr   =
          10 CmdrConnection.py:53 read: .apo =
39217 apo : pressure=3D21.355; windd=3D305.0; winds=3D6.2; gustd=3D310.3; =
gusts=3D8.1; airtemp=3D6.4; dewpoint=3D-1.4; dpErr=3DP; humidity=3D57.5; =
dusta=3D47301; dustb=3D9427; dustc=3D2673; dustd=3D1062; windd25m=3D22.7; =
winds25m=3D1.3; encl25m=3D16; truss25m=3D7.27; airTempPT=3D6.8; =
dpTempPT=3D-0.7; humidPT=3D58.8; irscmean=3D335; =
irscsd=3D59.10dusta is =
0.3u and dustb is 1.0u -- dustc and dustd are most likely the 3.5m =
counts.Is the standard for 1.0u <10k or 0.3u <10k? =
 I've no problem with it being the 1.0u number, but that should be =
spelled out in the procedure.The procedure should also suggest =
looking at that high humidity and then looking at an up to date forecast =
- NWS for example or another reliable source that provides a reasonably =
frequent update.  If the humidity is low and the forecast is for 0 =
chance of precip the following day, then waiting for <10k micron dust =
is a good standard.  If the humidity is currently high (say =
>30%) and the forecast indicates it will be around for a while, then =
the wise course is to probably cut the micron standard in half for =
opening or even to look at the 0.3u count instead.  Under such =
conditions the seeing is likely to be marginal in any case, so waiting a =
few more hours won't deprive us of any fantastic data.Kaike and Dmitry can set =
the actual standards as far as I'm concerned, what I've suggested above =
is just a guess and I can't really offer advice on the implications of =
types of observations (double exposure, etc).  I do think a =
discussion of checking tomorrow's forecast is an important bit to add =
though.Thanks,John---- Observing Summary ----We opened with a small delay because of =
dust. - Dust levels are large. We could not observe =
more than 3 hours for theaccumulated dust. PLEASE CLEAN =
THE MIRRORS. Delayed ventilating. Lots of =
clouds/radar. Huge dust cloud outside.Weather still poor, but dust starting to drop.=
--Apple-Mail=_381EB88E-91B4-4CA2-8BA6-BFA17B611DC5--