ChaMPlane Observation: CTIO/Hydra July 21-26, 2009

ChaMPlane Observation with CTIO 4m Hydra

July 21-26, 2009

!!This is the DARKEST run we ever have!!

!!!The first night is the DARKEST night of the 21st century!!!

During the first half of the first night of this run,

not only it's the new moon, but the earth will be shadowed by

the longest total solar eclipse of the 21st century!!!

I. Target Fields

Target Fields are listed in Table 1, sorted by RA. They include 8 ChaMPlane fields and 47Tuc (end-of-the-night field), where the BLS fields have the higher priorities. Other end-of-the-night fields are not listed here.

            Table 1. ChaMPlane CTIO/Hydra Observation Field List
MID  Mosaic  Field      RA(J2000)    Dec(J2000)      l         b       NH(e22)
------------------------------------------------------------------------------
 47  ctio04  J1550    15:51:09.73  -56:27:00.4  325.91867  -1.82233   0.926
  4  ctio00  J1655    16:54:33.35  -39:51:19.4  345.04135   2.36745   0.640
 49  ctio04  Mars     17:00:47.95  -26:59:02.7  356.03937   9.28077   0.132
 69  ctio08  BLSN2    17:40:24.04  -28:31:58.7  359.74142   1.18532   1.539
 70  ctio08  BLSN3    17:40:42.04  -28:12:07.8    0.05698   1.30471   1.214
 71  ctio08  BLSN1    17:43:04.08  -28:26:17.5    0.13141   0.73760   2.387
 72  ctio08  BLSS1    17:49:03.25  -29:14:45.6    0.12349  -0.80216   3.270
 52  ctio04  SW       17:54:24.77  -29:49:36.9    0.21811  -2.10101   0.479
	     47Tuc    00:24:05.67  -72:04:52.6  305.89484 -44.88930   0.018
------------------------------------------------------------------------------

II. Hydra Setup Files

Table 2 lists all the Hydra setup files observable for this run (sorted by RA). For each field, there are bright setups (R < 20) and faint setups (R => 20). (Some fields were divided at R=21 to move high priority targets into the bright setups.) Our data show that hydra is only effective for objects with R < 20. So we only observe bright setups in this run. For all the fields, only observe the first and/or second bright setups. (The first bright setups for fields J1550 and J1655 were observed in year 2008.) See the following section for priorities.

The faint setups are only listed here for reference. The very bright setups (R<13) are also only listed here for reference. These are targets that are too bright. If put in the bright setup, they will be way over saturated and therefore spill over to the neighboring spectra and damage them. Usually don't need to do the very bright setups. If there is a high priority target in the very bright setup, do it by putting a fiber in the center (just like doing the flux standard) is much quicker. The overhead time of fiber setup is too high for very few targets. However, you can do the very bright setups when the weather is bad and no good spectra can be taken for bright setups.

                    Table 2. ChaMPlane CTIO/Hydra Observation Hydra files 
                  Bright (13 < R < 20)                 Faint (R => 20)          Very bright (R<13)
Field  Total   1     2     3     4     5    Total   1     2     3     4     5           1
--------------------------------------------------------------------------------------------------------
J1550   579        90/r   89/r  85/r  81/r    1070  103/r  99/r  78/r  74/r  82/r         5/r
J1655    65        16/r    2/r   1/r   1/r    1404  107/r  114/r  105/r  99/r  100/r
Mars     87  53/r  27/r    7/r   0/r   0/r     342  89/r  81/r  75/r  47/r  26/r          4/r
BLSN2   699  24/r  97/r  100/r  91/r  80/r    1294  108/r  110/r  110/r  96/r  107/r    3/r
BLSN3   895  23/r 116/r  114/r 106/r 106/r    1781  112/r  107/r  119/r  111/r  109/r   7/r
BLSN1   298  92/r  75/r   57/r  31/r  21/r     603  105/r  95/r   89/r   86/r  85/r    14/r
BLSS1   387 104/r  99/r   82/r  47/r  24/r    1220  115/r  105/r  114/r  101/r  94/r    13/r
SW      968 106/r 101/r   91/r  99/r  87/r      43  39/r  4/r  0/r  0/r  0/r              1/r

47Tuc	     72d
--------------------------------------------------------------------------------------------------------
Total: Total number of bright or faint objects (without spectra yet) in the field.
1-5:   Number of bright or faint objects in the 1-5 hydra setups
Click a number to get that hydra setup file.
Click the "r" next to a number to get the region file of that setup.

Click a field name to get the detailed information of the hydra setups.
 where: 
  hydra_file:    hydra setup file.
  Center_RA,Dec: Center RA and Dec of the hydra setup.
  Sky:           number of sky positions.
  GS GSb GSf:    number of FOPS stars, with their bright and faint R mag.
  Obj Rb Rf:     number of objects, with their bright and faint R mag.
  X XRb XRf:     number of chandra counterparts, with their bright and faint R mag.
  Xha Xhab Xhaf: number of chandra-Ha sources (Ha-R<-0.3,SNR>5), with their bright and faint R mag.
  Xhm Xhmb Xhmf: number of chandra-Hm sources (Ha-R<-0.2,SNR>3), with their bright and faint R mag.
  H HRb HRf:     number of Ha emission sources, with their bright and faint R mag.
d: done (observed) - 7 setups, 470 objects.

III. Priorities

Under the perfect conditions, we can only observe 12 setups during this run (two setups per night for 6 nights). Table 3 gives the observing priorities of these 12 chosen setups. The priorities are sorted by Xha, Xhm, X, in that order. Each of the 12 setups has at least one Xha or Xhm source. 7 of the 12 setups have at least one Xha source. The first four bright setups for the 4 BLS fields have the higest priorities.

Table 3. ChaMPlane CTIO/Hydra Observation Hydra files sorted by priority

Pri  hydra_file  Center_RA    Center_Dec   Xha  Xhm    X    H  Obj
---  ----------  -----------  -----------  ---  ---  ---  ---  ---
 1   BLSN2_b1d   17 40 24.04  -28 31 58.7   14   10    0    0   24
 2   BLSN3_b1d   17 40 55.65  -28 15 07.8   11   10    2    0   23
 3   BLSN1_b1d   17 42 23.14  -28 26 17.5    3    1   88    0   92
 4   BLSS1_b1d   17 48 49.49  -29 17 45.6    1    8   73    0   82
 5   SW_b1d      17 54 38.25  -29 49 16.3    1    3   68   34  106
 6   J1550_b2d   15 51 08.60  -56 26 38.6    1    2   70   17   90
 7   J1655_b2    16 54 33.39  -39 51 19.4    1    0    8    7   16
 8   Mars_b1d    17 00 21.01  -26 56 02.7    0    5   31   17   53
 9   BLSN3_b2    17 40 55.65  -28 15 07.8    0    1  109    6  116
10   BLSN2_b2    17 41 05.01  -28 28 58.7    0    1   88    8   97
11   SW_b2       17 54 38.25  -29 49 16.3    0    1   64   36  101
12   BLSS1_b2    17 49 03.25  -29 20 45.6    0    1   33    0   34
------------------------------------------------------------------
Click the hydra file name to get that hydra setup file.
d: done (observed)

IV. Exposure Sequence

There are about 7.5 hours per night can be used to observe ChaMPlane fields. Take 5x37.5min exposures for each bright setup. Table 4 lists the exposure sequence for each setup, including setup fibers, acquire field and take comparison lamp. The total time needed for each bright setup is 3h55m. The fiber setup (20min) for the first observation of each night can be done during the twilight. So the two obsersations need exactly 2x3h55m-20m=7h30m!

When the time is running short, reduced the number of spectra. Each one will save 40min.

 Table 4. Exposure sequence for bright hydra setup
Do                     Exp  Readout  Total  Timeline
                      (sec)  (min)   (min)    (min)
-----------------------------------------------------
Setup hydra fiber                     ~20     20.0
Acquire field                          ~5     25.0
projector flat         5      2.5       2.5   27.5 
Arc lamp spectrum      3      2.5       2.5   30.0
Object spectra      2250      2.5      40.0   70.0
Object spectra      2250      2.5      40.0  110.0
Arc lamp spectrum      5      2.5       2.5  112.5
Object spectra      2250      2.5      40.0  152.5
Object spectra      2250      2.5      40.0  192.5
Object spectra      2250      2.5      40.0  232.5
Arc lamp spectrum     10      2.5       2.5  235.0
-----------------------------------------------------
Total time for each observation              3h55m

When the weather is bad and no good spectra can be taken for bright setups, take the very bright setups with a single 15min exposure. The total time needed for each very bright setup is 45min (assuming field acquisition has been done for the bright setups).

 Table 4. Exposure sequence for very bright hydra setup
Do                     Exp  Readout  Total  Timeline
                      (sec)  (min)   (min)    (min)
-----------------------------------------------------
Setup hydra fiber                     ~20     20.0
projector flat         5      2.5       2.5   22.5
Arc lamp spectrum      3      2.5       2.5   25.0
Object spectra       900      2.5      17.5   42.5
Arc lamp spectrum     10      2.5       2.5   45.0
-----------------------------------------------------

V. Observation Plan

Here is an observing elevation chart showing the locus of the target fields. Space between the two vertical dashed lines is the astronomical twilight zone.

postscript and CTIO 2009 July Ephemeris

Here are some observing guide:
Xavier's Hydra Guide
hydra cookbook
hydra-usermanual

Astronomical twilight: 19:30 - 6:09   Duration: 10h39m 
But all the ChaMplane targets are set at about 3:00am, so the actual usable time for ChaMplane is only 7h30m
Do two bright setups each night will need 7h30m*.
 *For the first field: Setup hydra fiber, Acquire field, projector
  flat, Arc lamp spectrum can be done in the evening before the
  twilight ends, so the first exposure can be started immediately at
  the beginning of the night.

So there is just enough time for two setups each with complete exposures sequence. If short of time due to weather or technical problems, try to reduce the number of exposures and/or exposure time.

VI. Flux Standard

Take flux standards every night when the target fields are set, i.e after 3am. To take the standard, move one fiber to the exact center, then point the telescope at the flux standard and take a spectrum. Remember to take a comparison spectrum after each standard taken.

VII. End of the night targets

There are 3h09m at the end of each night when all the ChaMPlane fields are set. The flux standards don't need that much time. The end-of-the-night fields should be observed during this time slot.

Wish you good weather and good luck! Enjoy the darkest night of the 21st century! Have fun!

Let me know if you have questions. Thanks!

Ping Zhao: zhao@cfa.harvard.edu