CTIO-1m Example Nightly Observing Plan

I. File Nomenclature

====================

To avoid confusion in the data reduction process (and to provide

some redundancy of information), we will standardize the file

naming convention for the different types of observations as so

(where YYYYMMDD is the UT date of the night and NNNN=a running

id number that is automatically generated):

Type of Observation File Name

------------------- ---------

biases bias.YYYYMMDD.NNNN.fits

darks dark.YYYYMMDD.NNNN.fits

dome flats dflat.YYYYMMDD.NNNN.fits

twilight sky flats sflat.YYYYMMDD.NNNN.fits

pointing standard point.YYYYMMDD.NNNN.fits (or possibly just "junk")

focus exposure focus.YYYYMMDD.NNNN.fits (or possibly just "junk")

linearity tests lintest.YYYYMMDD.NNNN.fits

exposure map tests expmap.YYYYMMDD.NNNN.fits

grid tests grid.YYYYMMDD.NNNN.fits

standard star fields std-"stdFieldName".YYYYMMDD.NNNN.fits (e.g., std-CDFS.0003.fits)

science targets sci-"targetName".YYYYMMDD.NNNN.fits (e.g., sci-M104.0010.fits)

For afternoon biases, darks, domes, etc., use the UT date of the coming night

(even if the actual UT date these afternoon exposures are the "day before".)

(Admittedly, trying to keep to this naming convention during the

heat of battle can be difficult, but it is good to try...)

II. Afternoon Tasks

====================

(Based heavily on text from J. Allyn Smith)

* EVERY AFTERNOON WE WILL OBTAIN A FULL COMPLEMENT OF BIASES AND DOME FLATS. *

INITIAL SETUP:

Set for 1X1 binning - this more closely mimics the pixel scale of the

DECam on the Blanco, and we shouldn't be rushed for time for the readout.

EACH AFTERNOON:

1. Obtain a set of 25 bias frames

2. Obtain a set of dome flats in each filter (g,r,i,z) - 10 each.

Getting counts of ~40K-50K electrons (??K-??K ADU), or about

1/3rd of the way to saturation, is good to aim for.

The following exposure times and Variac lamp voltage settings

are working well for the Nov 2009 run (might need to change

for the current run...):

filter exp time Variac setting Mean Counts

------ -------- -------------- -----------------

g 30 sec 60V ~93Ke- (bias=40Ke-)

r 30 sec 45V ~84Ke- (bias=40Ke-)

i 20 sec 40V ~80Ke- (bias=40Ke-)

z 15 sec 40V ~110Ke- (bias=40Ke-)

3. Obtain a set of 10 dark frames flats for each of the following

exposure times:

a. 10 sec

b. 30 sec

c. 60 sec

d. 100 sec

If you run out of time on a given afternoon, the dark frames are the

most expendable and can be skipped on that afternoon if necessary.

3. Copy the afternoon's data to Fermilab via rsync:

ssh -Y dtucker@des06.fnal.gov

cd /data/des06.a/data/DES_CTIO1m_Runs/Jul2010/

rsync -avz v1@ctios1.ctio.noao.edu:/ua82/data/\*.fits n1/

(here I am guessing that we have the visitor account "v1"

and that the data are on /ua82/data on ctios1; change as

appropriate).

You should do the rsync after the flats and also throughout the

night -- it will save time in the morning.

4. Copy the afternoon's data to the staging area on the Brazil Portal via FDT.

See http://twiki.on.br/bin/view/Documentation/FdtTransfer

and consult Marcio Maia (maia@on.br), Bruno Rossetto (rossetto@on.br),

and Luiz da Costa (ldacosta@on.br) for help.

=====

FIRST EVENING:

Set a time to meet the Ops Support person to go through setup

proceedures, first night help, whatever... This will probably be

after the twilight flats are done.

EACH EVENING (this assumes we will try twilight flats, esp. if

we want to try u-band twilights):

As a general note, this is the most hectic time of each night.

You'll be rushing to get through dinner, grab the night lunch and

head up the hill to be ready to go. Getting the twilight flats

going on time and fast enough to get as many as possible takes lots

of practice. It will come as time goes on.

1. When you get in the dome (even a few minute before sunset), store

your night lunch, put on soothing music (if you like), make sure any

data transfers are completed (if you started any in the afternoon).

2. Go up to the observing floor and do a walk around of the telescope.

Make sure TelOps has set it up correctly (they should, they're good).

(If you have to open the telescope, plan an extra 10-15 minutes to

do this).

3. Verify the clocks are correct and the telescope is pointed to

the twilight flat location (usually about -2 HA at -30 dec).

4. Set up the first twilight flat (Don't execute it yet).

5. Go outside and enjoy the sunset! Camera for the green flash if the

horizon is clear. Watch the viscachas play (or sun).

For the twilight sky flats in u, start out about 3-4 minutes after

sunset with a 5-6 second exposure, aiming for mean counts of ~20K-30K

ADU (test the first few for photon level). The timing will take some

getting used to. Keep taking twilight flats, gradually increasing the

exposure time to keep the mean counts at ~20K-30K ADU, until you are

taking 30-40 sec exposures. Because of the shutter issues, we may

only get u twilight flats. But, after 5 or so good (30+ sec) u flats,

you could change to the z,g,r,i filter and try some of those. If you

can get 5-6 good u flats each day and 1-2 good g, r, i, z flats each

day, we can build a good master frame.

Different chips respond in different ways, but on the CTIO-0.9m and

the USNO-1m I shoot the twilight flats in the order: u,z,g,r,i

(z response is poor, so it takes a bit more light than you might think).

Also, you want any stars that appear to median out after combining the

twilight frames, so you should either:

1. turn off the telescope tracking while taking twilights, or

2. use the handpaddle to dither the telescope pointing between

twilight flat exposures. (I generally prefer this method, but

either will work if you have enough frames.)

=====

SUNSET+2 minutes:

1. Back in dome, turn telescope tracking on (if you dither the flats).

At the 3-4 minute point, start the first twilight exposure. After

readout, examine it for level and adjust exposure time accordingly.

Remember the sky is getting darker while you are doing all this.

General rule: Once you're at the exposure level that you want, each

successive exposure will need about a 25% increase in exposure time.

(You'll probably have help for these next few steps on the first night.)

2. Late evening twilight:

a. use a bright star (mag < 5) to refine the pointing

of the telescope

b. focus the telescope

c. take an "art shot" of a bright (NGC or Messier) galaxy

to verify pointing.

======

DURING NIGHT:

1. At the beginning of the night, observe a set of 3-4 or so different

standard star fields, one near airmass ~ 1, one near airmass ~ 2,

and one or two at intermediate airmass (~1.5) (or 1.3, 1.7) (all 5 filters).

2. Observe target fields throughout the night, interspersing

them with the occasional standard star field. The target

fields should be observed at low airmass (preferably < 1.3;

definitely < 2.0); the standard star fields should be

observed a variety of airmasses between 1 and 2.

3. Sometime during the night (preferably relatively early), do a

Star Flat/Stellar Linearity Test.

It is best if the field is observed at low airmass (< 1.3).

This set of observations can be treated as one of your standard

star fields.

4. In the middle of night, take 5-10 biases as a check on bias stability.

5. Periodically (every hour or so), go outside the dome and check sky

conditions by eye. (Note, it can take up to 15min to dark adapt.)

Note your findings in the manual observing log.

====

END OF NIGHT

1. At the end of the night, again observe a set of 3 or so

different standard star fields (all 5 filters) and 5-10 more biases.

2. Shut down and stow telescope, fill the dewar, fill out night logs.

3. At the end of the night, save the following data, which can later

be used to help determine the quality of the night:

a. The CTIO Environmental data from

http://www.ctio.noao.edu/environ/environ.html b. The 10-micron GOES East satellites animated GIF movie for the night from http://www.ctio.noao.edu/sitetests/GOES/movies/ c. The TASCA all-sky animated GIFS for the night from http://ctmt02.ctio.noao.edu/allsky.htm 4. Start an rsync of the night's data (including the ancillary data from Step 9) to des06.fnal.gov:/data/des06.a/data/DES_CTIO1m_Runs/Jul2009/Raw 5. Start an FDT transfer of the night's data to the staging area on the Brazil Portal. 6. GET SOME SLEEP! The madness will start again all too soon.