Champlane Observation: CTIO 4m/MosaicII May 13-17, 2001

Champlane Observation

CTIO 4m/MosaicII May 13-17, 2001

Target List
Exposure Sequence
Observation Plan
Landolt Standards
Biases and Flats

Fields Observed


Night                          Observed
----------------------------------------------------------------------------------------------
5/15    V382Vel(R&Ha)   PSR1813
5/16	NGC3603         PSR1706     MWC297(R&Ha) 
5/17    V382Vel(V&I)    4U1538      PSR1757         SGR1900(R&Ha)   MWC297(V&I)
----------------------------------------------------------------------------------------------

Observing Plan for the Last Night of This Run

Posted May 17, 2001

The night of May 16 was a very good one. NGC 3603, PSR B1706-44, MWC297(R&Ha) were taken. Following is the suggested observing plan for the last night. If we can finish this plan tonight, we will have completed 8 out of the 15 selected targets.

              Revised Champlane CTIO 4m/MosaicII Observation Plan, May 17

Night                               Do
----------------------------------------------------------------------------------------------
5/17    V382 Velorum(V&I), 4U 1538-52, PSR B1757-24, SGR1900+14, MWC297(V&I)
----------------------------------------------------------------------------------------------

If there is time to do 1x3 dithered V&I, do it. Otherwise, shorten the V&I to a single 3min exposure with no dither. And take some Landolt standards if possible.

Revised Observing Plan

Posted May 16, 2001

In the night of May 15, V382 Velorum 1999(R&Ha) and PSR 1813-36 were taken, although the weather was not optimal. Here is the observing plan for the rest two nights (May 16-17). G21.5-0.9 is removed. SGR1900+14 is kept even it has lower priority, because it can be observed in the upcomiong WIYN run in September.

              Revised Champlane CTIO 4m/MosaicII Observation Plan, May 16-17

Night                               Do
----------------------------------------------------------------------------------------------
5/16    NGC 3603 		PSR B1706-44		MWC297
5/17    4U 1538-52		PSR B1757-24		SGR1900+14
----------------------------------------------------------------------------------------------

The best time to do I filter correction frames is at the beginning of night 5/17, before observing 4U 1538-52.

Revised Observing Plan

Posted May 15, 2001

Because the second night (May 14) was lost to the weather again, following is a revised observing plan. Another three targets (priorities 7, 10, 12) are removed. This plan does not split fields into two nights to observe like previous plans (which was the only solution because of lacking early night targets), so it saves some overhead time. This plan assumes the next three nights (May 15-17) are clear so the rest of the 9 fields can be observed. If not, another revised plan will be posted here.

              Revised Champlane CTIO 4m/MosaicII Observation Plan, May 15-17

Night                               Do
----------------------------------------------------------------------------------------------
5/15    V382 Velorum 1999	PSR 1813-36		MWC297
5/16    NGC 3603 		PSR B1706-44		G21.5-0.9   
5/17    4U 1538-52		PSR B1757-24		SGR1900+14
----------------------------------------------------------------------------------------------

The best time to do I filter correction frames is at the beginning of night 5/17, before observing 4U 1538-52.

Revised Observing Plan

Posted May 14, 2001

Because the first night (May 13) was clouded out, following is a revised observing plan. Three targets with the lowest priorities are removed. This plan assumes the next four nights (May 14-17) are clear so the rest of 12 fields can be taken. If not, another revised plan will be posted here.

              Revised Champlane CTIO 4m/MosaicII Observation Plan, May 14-17

Night                                          Do
----------------------------------------------------------------------------------------------
5/14    V382 Velorum 1999(R&Ha), XTE J1723-376, MWC297, G21.5-0.9(V&I)
5/15    NGC 3603(R&Ha), SAX J1747.0-2853, GALACTIC PLANE, SGR1900+14(V&I)
5/16    V382 Velorum 1999(V&I), NGC 3603(V&I), PSR B1706-44, G21.5-0.9(R&Ha), SGR1900+14(R&Ha)
5/17    4U 1538-52,PSR1813-36,PSR B1757-24
----------------------------------------------------------------------------------------------

For two targets (PSR B1706-44 and 4U 1538-52), the airmass will be around 2 to start with. But it will get better as the time goes on.

If the I filter correction frames are needed, the best time to do it is in night 3 after V382 Velorum 1999(V&I), NGC 3603(V&I) and before PSR B1706-44. Or it can be done at the beginning of night 4. Those are the times when one of those three targets have the airmass around 2.

I. Target List

For the Champlane optical observation at CTIO 4m/MosaicII on May 13-17, 2001, 15 fields are selected from Chandra cycle 1 & 2, calibration, TOO and DDT target lists. All fields have |b|< 10 degree and Exp >= 20ks, with clean optical and X-ray backgrounds. 14 out of 15 fields are observed with Chandra ACIS, which are operated under TE mode and at least have 4 CCDs turned on. One of the fields is observed with Chandra HRC-I. The goal is to observe 3 fields per night for 5 nights. Here is the target list:

                                  Champlane CTIO 4m/MosaicII Target list, May 13-17

                                Telescope pointing
                                Center of Mosaic II                         Chandra  Chandra            Chandra
Pri Field           Observed?   RA        Dec (J2000)   glong       glat     Detect    Exp      nH      Status
------------------------------------------------------------------------------------------------------------------
 2  V382 Velorum 1999        10 44 48.00  -52 18 18.0  284.16783    5.77136  ACIS-I   35.00  3.73E+21   archived
11  NGC 3603                 11 15 49.80  -61 17 23.0  291.62597   -0.52966  ACIS-I   50.00  1.30E+22   archived
 6  4U 1538-52               15 42  1.40  -52 18 22.0  327.42034    2.16449  ACIS-I   24.00  9.86E+21   observed
14  G327.1-1.1           N   15 54 49.00  -55 04  6.0  327.14982   -1.04248  ACIS-I   50.00  1.57E+22   unobserved
 4  PSR B1706-44             17 09 42.00  -44 30 45.0  343.10055   -2.68183  HRC-I    50.00  8.86E+21   archived
12  XTE J1723-376        N   17 23 59.70  -37 42  8.6  350.18332   -0.87329  ACIS-I   30.00  1.33E+22   unobserved
10  SAX J1747.0-2853     N   17 47 33.10  -28 53 37.0    0.22055   -0.25874  ACIS-I   30.00  1.09E+22   unobserved
 5  PSR B1757-24             18 01 48.00  -24 49 39.0    5.25588   -0.88147  ACIS-S   20.00  9.26E+21   observed
 1  PSR1813-36               18 16 25.00  -36 20 29.5  356.80212   -9.37407  ACIS-S   30.00  1.25E+21   unobserved
 3  MWC297                   18 27 59.80  -03 51  2.6   26.80561    3.52259  ACIS-I   40.00  4.92E+21   unobserved
 8  G21.5-0.9            N   18 33 40.20  -10 35 54.0   21.50135   -0.88293  ACIS-I  100.00  1.25E+22   archived
15  KES 73               N   18 40 47.80  -04 53 50.0   27.38696   -0.00538  ACIS-S   40.00  1.98E+22   observed
 7  GALACTIC PLANE       N   18 43 37.80  -04 03 33.0   28.45015   -0.19668  ACIS-I  200.00  2.07E+22   archived
 9  SGR1900+14               19 07 38.30  +09 18  8.1   43.02246    0.76591  ACIS-I   30.00  1.42E+22   unobserved
13  W49B                 N   19 10 54.00  +09 15 25.9   43.26443   -0.18230  ACIS-S   40.00  1.86E+22   observed
------------------------------------------------------------------------------------------------------------------

Priorities are sorted by nH, Exp, glat, and field X-ray and optical background. 1 is the highest, 15 is the lowest.

The RA and Dec are for the telescope pointing (not the coordinates of the targets or the Chandra), based on the overlay of Mosaic II on ACIS. NO MORE OFFSET IS NEEDED.

Click a object name to see the MosaicII & ACIS/HRC overlay on DSS image. This should help to identify the field. Note that the DDS images are E-left & N-up. But the Mosaic images are E-up & N-right.

II. Exposure Sequence

For each field, do the following Exposure Sequence to achieve the project goal - reach 24th mag.

Do dithers for the long exposures are very important. Not only it fill up the gaps between CCDs 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

Filter  Frame         Exp   Exp+readout Total Timeline
                     (sec)  (min/frame) (min)   (min)
------------------------------------------------------
R       single image     3       2.5     2.5     2.5
Ha      single image    30       3.0     3.0     5.5
R       dither 1x5     240       6.5    32.5    38.0
Ha      dither 1x5    1500      27.5   137.5   175.5
V       dither 1x3     180       5.5    16.5   192.0
I       dither 1x3     180       5.5    16.5   208.5
------------------------------------------------------
1. Exp is the exposure time for each image in seconds.
2. Exp+readout is the exposure plus 2.5min readout time for each image.
3. Total is the total time ((Exp+readout) x dither) for each filter.
4. Timeline is the accumulated time for each field.

Under Frame:
A. single image: take one short exposure each for R and Ha filter.  No dither.   

B. dither 1x5: Use command "mosdither" to do one set of standard dither pattern 
   of 5 positions for R and Ha 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. dither 1x3: Use command "mosdither" to do one set of dither pattern of 3
   positions for V and I filters.  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.

III. Observation Plan

The astronomical twilight on May 13-17 ranging from 10:36:43 (636.7 min) to 10:40:37 (640.6 min). Above exposure sequence requires 208.5 min (including readout time) for each field. Three fields need 625.5 min. This leaves very little time for everything else, including slew the telescope, locate the new field, and do the standard. Therefore careful planing is needed.

A. First of all, the about exposure sequence is the most time can be spent on ech field. When time is running short, first reduce the number of I images, then V images. But keep at least one V and one I images. When only take one V and one I images, the total time needed for a field is reduced to 186.5 min.

B. As you can see from the chart below, there is a little short of targets in the early night. Only two targets can be observed with airmass < 2 at the beginning of the night. Thus we need to split the observation of the first two targets into different nights.

C. Try to start 10-15 min before and end 10-15 after the astronomical twilight zone to get a little more observing time. Here is a suggested observation plan:

              Champlane CTIO 4m/MosaicII Observation Plan, May 13-17

Night	                                       Do
----------------------------------------------------------------------------------------------
1       V382 Velorum 1999(R&Ha), XTE J1723-376, MWC297, G21.5-0.9(V&I)
2       NGC 3603(R&Ha), SAX J1747.0-2853, GALACTIC PLANE, SGR1900+14(V&I)
3       V382 Velorum 1999(V&I), NGC 3603(V&I), PSR B1706-44, G21.5-0.9(R&Ha), SGR1900+14(R&Ha)
4       4U 1538-52,PSR1813-36,W49B
5       G327.1-1.1,PSR B1757-24,KES 73
----------------------------------------------------------------------------------------------

For Three targets (PSR B1706-44, 4U 1538-52 and G327.1-1.1), the airmass will be around 2 to start with. But it will get better as the time goes on.

If the I filter correction frames are needed, the best time to do it is in night 3 after V382 Velorum 1999(V&I), NGC 3603(V&I) and before PSR B1706-44. Or it can be done at the beginning of night 4 or 5. Those are the times when one of those three targets have the airmass around 2.

Here is an observing chart showing the locus of the 15 objects during the night. Horizontal axis is the time in hours. Space between two gray bars are the astronomital twilight zone. Versitcal axis is the distance of the object above horizon in 10-degrees.

postscript and txt

Here is an observing almanac made for this run. Download it here and print it out.

IV. Landolt Standards

Take a set of Landolt standards (VRI) at the beginning of each night. And once more during the night when changing targets if possible. Don't do it at the end of the night, because we have a lot of targets at the end of the night but not enough at the beginning.

V. Biases and Flats

Take biases and domeflats (V R I & Ha) in the afternoon. Dark is not necessary. Take sky flats if possible.

Call me anytime if there are questions: 617-496-7582 (office), 781-646-0611(home)

THANKS!

Ping

Ping Zhao: zhao@cfa.harvard.edu