- Coordinates:
RA (2000) 21 17 08.3
Dec (2000) +34 12 27
Magnitude 13.2 (B)
Consult the finder charts
for more information.
- Headquarters:
- The XCov 24 Headquarters (HQ) is in Ames, Iowa.
The HQ will contact each site at
the beginning of the night for a time check and site update. Consult the Phone Contact List for information on phone, fax,
and email for the control center as well as the other sites for this run.
- Time:
- Please do a clock time check each night before
taking data and verify your time with HQ at the beginning of the run, and
as often during the run as possible. HQ will have an accurate clock
available for phone clock checks. You can also check your time against the USNO
Java
Clock.
If your clock shows drift during the night, report the number of seconds to HQ so it
can be accounted for in the data reduction.
If your clock runs fast, that is a "positive" drift, and a slow clock is a
"negative" drift.
- Run start:
- Please start your run on an integral multiple of
ten seconds (times ending in "0"), or as close as possible.
Check the computer clock just before the start
of a run, synchronizing with your master clock to within 0.1 sec if
possible.
- Observing Logs:
- We ask that you keep an accurate log of the night,
including observers, apertures, integration time, etc., and send
a copy of your observation log along with the data.
- Data Transfer:
- We will be reducing the data as fast as they come in, and we'll
contact you promptly if we have any questions about, or problems with, the
data you send. There are two ways to send your data and logs at the
end of each night.
- Via e-mail to: wet@wet.physics.iastate.edu directory.
- By FTP to: wet.physics.iastate.edu
The username for the FTP site
and the password is available through email. This information is only
available through email because we have had problems with hackers filling the
FTP system in the past. This is not an anonymous FTP transfer, so you will
need the username and password to upload your data.
If you use the FTP option, load your data into the
"wet/incoming/xcov24/"
WET HQ is not set up to handle the large volume of image data that CCD systems produce. CCD
observers should only submit a data file consisting of the extracted photometry.
- PMT observers
- Integration times: For telescopes greater than 1m, use a
5 second integration. For telescopes smaller than 1m, use a 10 second
integration.
- Filters: Use NO filters in any channel.
- Guide Stars: Please consult the finder chart.
Record your ch2 offsets and telescope plate scale
so we can determine exactly which star was observed.
- Sky calibration: Observers who observe the
sky continuously in one channel (the usual method for 3-channel photometers)
should
record sky in all three channels near the beginning and
the end of each
run to permit accurate cross calibration.
Observers with
2 channel photometers should observe a comparison star with the second
channel and take sky by moving the
telescope. Try to take sky as often as
needed, at least once per 1/2 hour, for 4 or 5 good sky
points; more are not needed and cause unwanted data gaps
in the light curve of the target star. Try not to take sky measurements on a
regular cycle, as that creates unwanted periodicity in the data.
- Apertures: Please use the smallest aperture consistent with getting
data of good quality (e.g. no visible loss of light to the
edge of the aperture). A general rule of thumb is to use
an aperture approximately 8-10 times the diameter of the
seeing disk. Record the size of the aperture (in arcsec)
in your observing log.
- CCD observers
- Calibrations for CCDs: Proper calibration of CCD data is crucial to
the success of this campaign. Be sure to take the appropriate calibration
frames for every data run on every night. And if in doubt about how many
calibration frames to take, remember that it's always better to have too
many calibration frames than not enough!
- Bias frames: Take at least 10 zero length exposures (or as short an
integration time as your system allows) with the shutter closed
at the beginning and end of each data
run. If it is necessary to adjust your observing system during a data run
(such as filling a dewar), then take additional bias frames before and after
this change.
- Dark frames: Take at least 10 dark frames with the shutter closed
at the beginning and end
of each data run. The integration time for the dark frames should be as long as
the integration for your data frames or flat fields, whichever is longer. If you are using different
integration times for different WET targets, then use the longest of those times for your
dark integration time.
If possible (likely only on a clouded out night),
take a series of long dark exposures (1000s or so) so a comparison
of the dark time over the short exposures can be made.
- Flat fields: Take at least 10 flat field frames at the beginning of
each data run. Choose an exposure time for your flat fields so that the counts
for the CCD are about 50% of the saturation level. We leave it to you if you
prefer to take sky or dome flats.
- Integration times: For telescopes greater than 1m, use a
5 second integration. For telescopes smaller than 1m, use a 10 second
integration.
The cycle time of observations (the time between the start
of two observations) should not exceed twice the integration time if possible.
Please try to keep the cycle time for
your observations as constant as possible, and keep the readout time as short as possible.
If these guidelines are problematic, then observers should use
their judgement to determine the integration time that gives the best balance between signal
to noise ratio, cycle time and duty time.
- CCD binning and window: If possible, change the binning of your CCD to decrease
readout time, but be sure that there is still sufficient area around the target and
comparison stars for aperture extraction. If your CCD software allows you to window the
frame (i.e. read out only a portion of the frame), be sure to leave at least two comparison
stars in the window, as well as a clear area that can be used for sky calibration.
- Filters: Telescopes under 1m should use NO filter. Telescopes over 1m should use a filter
if necessary. Use, in order of preference, CuSO4, BG39, BG40
(a 2mm BG40 matches a BG39 but is more durable), and then B as a last
resort. A typical B filter consists of a BG39 filter plus a blue cutoff;
if you have such a 2 filter combination, then you can just use the BG39
filter. If none of these options are available, then contact HQ for
instructions.
- Comparison Stars: Please consult the finder chart.
- Photometry extraction: The WET does not have a standard photometry extraction
package yet, so CCD observers will need to reduce their data with their own software. The
output of this software must be converted to the standard WET format. If you are unable to do this, contact HQ for instructions..
- Data format: There is a set format for CCD data submitted to HQ summarized on
this page. If you are
unable to submit your data in this format, then please contact Reed directly to discuss the format of your submitted
data.
- Final analysis:
- CCD observers, we would appreciate if you could do the
basic reductions (overscan, bias, dark count, flat field corrections)
yourself and send us the raw and reduced science frames after
the run, along with an explanation of your reduction procedure.
If you can't do this, please send us all your raw frames. We ask
you to mail CDROMs containing the data FITS files (and any other associated files) to:
Steve Kawaler
Iowa State University
Department of Physics & Astronomy
Ames, IA 50011
USA
Please keep a copy of your data and logs in case some mail gets lost.