• Target List
• Exposure Sequence
• Observation Plan
• Biases, Flats etc.

I. Target List

Following is the target list sorted by increasing RA. The RA and Dec in the list are the telescope pointings, i.e. the center of the MosaicII (not the coordinates of the targets or the Chandra), based on the overlay of Mosaic II on ACIS. NO MORE OFFSET IS NEEDED.

Priorities are sorted by ACIS-I over ACIS-S, lower NH, and longer Exposure time. 1 is the highest priority, 15 is the lowest priority.

                       Champlane CTIO 4m/MosaicII Target list   May 16-20, 2004

                            Telescope pointing
                            Center of Mosaic II                                          Chandra
Pri Field	           RA         Dec(J2000)      l         b       NH(e22)   Exp   Instru  ObsID
-----------------------------------------------------------------------------------------------------------
 9  G309.8+0.0           13 50 12.00  -62 09 36.0  309.73349  -0.06672   7.820   40.00  ACIS-I   2804
10  PSRJ1509-5850        15 09 36.00  -58 48 18.0  320.01084  -0.59235   5.707   40.00  ACIS-S   3513
 8  G322.5-0.1           15 24 00.00  -57 06 53.2  322.52437  -0.16386   4.329   31.00  ACIS-I   2784
 5  XTEJ1550-564         15 51 01.07  -56 27 16.6  325.90034  -1.81328   0.940  210.00  ACIS-S   5190,3807,4368,3448,3672,1965
 7  MZ3                  16 17 09.70  -51 59 30.2  331.71681  -1.00867   1.130   40.00  ACIS-S   2546
14  SGR1627-41unobserved 16 35 51.69  -47 37 30.9  336.94961  -0.13501  26.660   75.00  ACIS-S   1981,3877
 1  MARS                 17 00 48.53  -26 58 24.2  356.04934   9.28549   0.131   30.00  ACIS-I   1861
 4  XTEJ1709-267         17 09 36.71  -26 36 53.0  357.51979   7.91660   0.361   24.00  ACIS-I   3507
15  NGC6334   unobserved 17 20 41.45  -35 56 24.0  351.26547   0.58919  54.942   80.00  ACIS-I   2573,2574
12  TORNADO              17 40 00.00  -30 57 59.2  357.63298  -0.03307  10.550   21.00  ACIS-I   2687
 3  Stanekwindow         17 54 24.42  -29 49 16.3    0.22241  -2.09703   0.476  100.00  ACIS-I   4547,5303
 6  4U1755-33            17 58 49.20  -33 51 00.0  357.19408  -4.92093   0.410   74.00  ACIS-S   3510,4586
 2  BAADE'SWINDOW	 18 03 36.00  -29 57 50.7    1.08908  -3.89740   0.314  100.00  ACIS-I   3780
13  G11.4-0.1            18 11 20.40  -19 14 24.0   11.32621  -0.22863  10.879  100.00  ACIS-I   3512,3910,3911,780,3912,3909
11  PSRB1823-13          18 26 00.00  -13 37 12.0   17.94011  -0.66268   6.379   40.00  ACIS-S   2830
-----------------------------------------------------------------------------------------------------------

Click a object name to see the MosaicII & ACIS overlay on DSS image. This should help to identify the field. Click a Chandra ObsID to see the X-ray source plots by XPIPE. Note that the DSS images and XPIPE plots are E-left & N-up. But the MosaicII display at the CTIO is E-up & N-right.

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II. Exposure Sequence

Do dithered exposures for the long exposures are very important. Not only it fills up the gaps between the chips and eliminate bad columns to make a cosmetically clean image, it also greatly reduce the "bleeding" effect caused by saturated bright stars.

           Exposure sequence for each field

N  Filter  Frame         Exp   Exp+readout Total Timeline
                        (sec)  (min/frame) (min)   (min)
---------------------------------------------------------
1  R       single image     2       1.7     1.7     1.7
2  Ha      single image    30       2.2     2.2     3.9
3  R       dither 1x5     240       5.7    28.5    32.4
4  Ha      dither 1x5    1500      26.7   133.5   165.9
5  V       single image     2       1.7     1.7   167.6
6  I       single image     2       1.7     1.7   169.3
7  V       dither 1x5     180       4.7    23.5   192.8
8  I       dither 1x5     180       4.7    23.5   216.3
---------------------------------------------------------
1. N is the exposure sequence number.
2. Exp is the exposure time for each image in seconds.
3. Exp+readout is the exposure plus 1.7min readout time for each image.
4. Total is the total time ((Exp+readout) x dither) for each filter.
5. Timeline is the accumulated time for each field.

Under Frame: 

A. single image: take one short exposure for each filter.  No dither.

B. dither 1x5: Use command "mosdither" to do one set of standard dither pattern 
   of 5 positions for R, Ha and V filters.  Take one image at each position. 
   The standard dither pattern is at "ditherdb$todd.dat".

It looks like this:
===========
# Tod Lauer's canned dither scheme for the NOAO mosaic 

# Offset relative to current telescope position 

# RA (pixels) Dec (pixels) 

0 0 

160 -240 

-160 240 

80 120 

-80 -120 
==============

C. When short of time, dither 1x3 can be used for filters I and V: 
   Use command "mosdither" to do one set of dither pattern of 3.  Take
   one image at each position. Create and use a "ditherdb$dither3.dat"
   file like this:

===========
# Dither 3 positions.

# Offset relative to current telescope position

# RA (pixels) Dec (pixels)

0 0

160 -240

-160 240
===========

OR, simply use the standard dither pattern and stop it after 3 exposures.

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III. Observation Plan

A. Try to start 10-15 min before and end 10-15 after the astronomical twilight zone to get a little more observing time.

B. When time is running short, do the following to save time:

a. First reduce the number of I images to dither 1x3. (save 9.4 min)

a. Then reduce the number of V images to dither 1x3. (save 9.4 min)

b. Skip V and I short (2 sec) images. (save 1.7 min each)

c. Reduce one or two more I deep images, then V deep images. (save 4.7 min each) But keep at least one V and one I images.

When take only one deep V and one deep I images, the total time needed for a field is reduced to 175.3 min - a total saving of 41.0 min.

postscript and txt

Here is an observing almanac made for this run.

Here is the CTIO 2004 Ephemeris.

Here is a suggested observation plan for the 5 nights.

Night                   Do
-------------------------------------------------------------
5/16    XTEJ1550-564    MARS          BAADE'SWINDOW
5/17	MZ3             Stanekwindow  XTEJ1709-267
5/18	G322.5-0.1	4U1755-33     PSRB1823-13
5/19	G309.8+0.0	TORNADO       G11.4-0.1 
5/20	PSRJ1509-5850   SGR1627-41    NGC6334
-------------------------------------------------------------

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IV. Biases, Flats etc.

• Biases and Domeflats: Take biases and domeflats in the afternoon before dinner.
• Skyflats: Take twilight skyflats starting shortly after sunset at around 6:00pm.
• Pointing and Focus: Do telescope pointing and focus after the skyflats at around 6:40pm.

1. Biases and Domeflats

2. Skyflats

• Point the telescope to zenith at sunset at 6:05pm.
• Turn the tracking on during the skyflat exposures and turn the tracking off during the readouts so there will be an offset between exposures.
• Do the Ha filter skyflats first, then do the I filter skyflats.
• Start at about 6:10pm, take a 2 seconds Ha skyflats. Examine the image and make the adjustment of the exposure time so the flat has about 10000 counts.
• Take the first Ha skyflats with adjusted exposure time (remember to turn the tracking on during exposure and off during readout).
• Take the second Ha skyflats with exposure time twice as long as the first exposure (e.g.: first is 5sec, second one should be 10sec). The sky gets darker during the 1.7 min readout. To double the exposure time is just about to compensate the change in the sky.
• Take at least 3 Ha skyflats.
• Take at least 3 Ha skyflats.
• If the exposure time is still under 30sec, continue to take the Ha skyflats until the the exposure time is over 30sec.
• Take the first I filter skyflat with exposure time equal to 1/10 of the last Ha skyflat exposure. Examine the image to make sure it gets about 10000 counts. Adjust exposure time if needed.
• Take the second I filter skyflat with exposure twice as long as the first.
• Take at least 3 I skyflats.

3. Pointing and Focus:

• Stop the skyflats at around 6:40pm.
• Do the pointing and focus at around 6:40pm.
• Start to observe the first ChaMplane field at about 7:00pm.

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THANKS!

Ping Zhao: zhao@cfa.harvard.edu