Hello, SMARTS, Chilean, and NOAO users! 01 JAN 2012
Welcome to SMARTS 2012A.
You are being contacted because you have been granted service time on
the CTIO 0.9m telescope in the 2012A observing semester, beginning
01 JAN 2012. This email is a brief overview of the SMARTS scheduling
process for the 0.9m, the instrumentation, and tips on planning
observations (in that order). For convenience, it is also online here:
http://www.astro.gsu.edu/~thenry/SMARTS/smarts.0.9m.welcome
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C O N T A C T P E O P L E
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The responsible authorities for the SMARTS 0.9m are:
Mr. Adric Riedel (GSU), SMARTS Fellow for the 0.9m.
riedel@chara.gsu.edu
Ms. Jennifer Winters (GSU), SMARTS Fellow for the 0.9m.
winters@chara.gsu.edu
Dr. Todd Henry (GSU), SMARTS 0.9m Coordinator.
thenry@chara.gsu.edu
Dr. Charles Bailyn (Yale), Director of the SMARTS Consortium.
charles.bailyn@yale.edu
Questions about 0.9m operations should be directed to Mr. Riedel,
Ms. Winters, and Dr. Henry; GSU has been using the 0.9m since 1999 and
has been coordinating the 0.9m since the beginning of SMARTS in 2003.
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S C H E D U L I N G
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Time on the SMARTS 0.9m is a mix of classical user observing and
service observing, divided into (generally) alternating blocks of
nights the CTIO staff call 'turnos'. Within any given turno, time is
alloted on specific nights (or half-nights, but not less). As such,
we cannot guarantee weather conditions.
Note that as of 2012A, the CTIO 0.9m 'turnos' are no longer uniformly
seven nights starting on a Thursday, as SMARTS is now running the
user-only CTIO 1.0m and the user/service CTIO 0.9m on an alternating
schedule.
The overall SMARTS 0.9m page can be found at:
http://www.astro.gsu.edu/~thenry/SMARTS
The observing schedule for 2012A is posted (and updated) here:
http://www.astro.gsu.edu/~thenry/SMARTS/schedule2012A.htm
Under the 'TIMES' link for your night(s), you will also find a listing
of precisely what hours you have been given. This will aid in
planning your programs. Notice that, after the southern autumnal
equinox, 20 MAR 2012, a one-hour break mandated by the Chilean federal
government has been explicitly programmed into the schedule.
Unless you wish to keep your program completely confidential, this is
also where it will be posted for the service observers to see.
Three weeks before your scheduled observations' turno, you will be
contacted by Adric Riedel or Jen Winters, who will send you a template
(also available at
http://www.astro.gsu.edu/~thenry/SMARTS/smarts.template
and attached to this email) to use to plan your program. Reminders
will be sent two weeks before, and 10 days before, as needed.
***** IF YOU DO NOT RESPOND WITH AN OBSERVING LIST BY 7 DAYS *****
***** BEFORE YOUR TURNO BEGINS, YOU WILL FORFEIT YOUR TIME. *****
You are welcome to contact Mr. Riedel or Ms. Winters with questions
about your observing program. Also, example telescope setups from
regular users may be found here:
http://www.astro.gsu.edu/~thenry/SMARTS/setups.dir/index.htm
You will also need to fill out the instrument form at
http://www.ctio.noao.edu/forms/supportforms/ccd_direct.php
(using 0.9M+Tek 2048 CCD) to confirm your time and request the filters
you will need. This is critical for the 0.9m in order to be sure that
your desired filters are available.
After your observations are complete, Mr. Riedel or Ms. Winters will
contact you again with the night reports from your scheduled nights
and instructions on how to download the data from GSU's FTP server.
Data will be held there for 30 days as bzip2-compressed fits files
plus a text file with brief header information.
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I N S T R U M E N T A T I O N
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---------------------------THE INSTRUMENT-----------------------------
Pictures of the instrument:
http://www.astro.gsu.edu/~thenry/SMARTS/smarts.0.9m.pictures
The SMARTS 0.9m is a 36-inch (91-cm) Boller & Chivens telescope, built
in 1965 and currently operated by the SMARTS Consortium for NOAO.
The only available instrument on the 0.9m is a Tektronix 2048x2046 CCD
with 65K pixel/ADU depth (linear to 60K ADU), and a FOV of 13.69' on
the sky (north down, east left), with a pixel scale of 0.401"/pix (not
0.396"/pix as listed on the CTIO page below). This arrangement has
lasted for more than 14 years, and has been incredibly stable, both
photometrically and astrometrically.
More detailed (somewhat outdated) information about the following
points may be found here:
http://www.ctio.noao.edu/telescopes/36/0-9m.html
The Tektronix CCD can be run in a number of modes:
FULL chip (13.6'), ONE amp readout (3 min readout)
FULL chip (13.6'), QUAD amp readout (0.8 min readout)
Central QUARter (6.8'), ONE amp readout (0.8 min readout)
Central QUARter (6.8'), QUAD amp readout (0.3 min readout)
Quad-readout frames will need to be processed with a tool like IRAF's
quadproc, as each of the amplifiers has its own bias level. In
single-amp mode, the lower left (ll) amplifier is usually used.
Dual-amp mode and 2x2 binning are also possible, but not officially
supported.
There are also three available gain settings (read noise is for ll
amp:)
1: (unavailable, failed in March 2009)
2: Read Noise ~ 1.5 ADU = 3.9 e-
3: Read Noise ~ 1.7 ADU = 3.1 e-
4: Read Noise ~ 2.6 ADU = 2.6 e-
(values updated 2012A by Dr. John Subasavage, this supercedes the CTIO
website)
----------------------------THE FILTERS-------------------------------
The 0.9m accepts two filter wheels. There are two sizes available,
8-slot wheels for 3"x3" filters, and 5-slot wheels for 4"x4" filters.
CTIO has a large assortment of filters available for use, listed here
(many linked to their filter traces):
http://www.ctio.noao.edu/instruments/filters/filters_34.html
CTIO also has some old 2"x2" filters useable in the 0.9m, listed here:
http://www.ctio.noao.edu/instruments/filters/index.html
Using the 2"x2" filters is not recommended --- many of them are
seriously degraded and all of them vignette on the 0.9m in FULL chip
mode.
In addition to those filters, CTIO has a set of 3x3 Neutral Density
filters:
ND1 attenuation by = 2.5 MAGNITUDES
ND2 attenuation by = 5.0 MAGNITUDES
ND3 attenuation by = 7.5 MAGNITUDES
ND4 attenuation by = 10.0 MAGNITUDES
it is also possible to combine two ND filters (e.g. ND2+ND4=15.0 mag
attenuation).
The 0.9m uses a 3x3 color-balance filter for dome flats (but not sky
flats). It is not necessary to request this filter; it is used
automatically.
Please make your filter request as specific as possible when you fill
out the instrument form. These filters are shared between telescopes
so CTIO staff will need time to make sure the right ones are available
for the 0.9m on your nights.
http://www.ctio.noao.edu/forms/supportforms/ccd_direct.php
The most common filters in use at the 0.9m are:
* The Tektronix UBVRI 3"x3" filter set (roughly
Johnson/Kron-Cousins), which is almost always comprised of the Tek
#2 UBRI filters and the Tek #1 V filter. Filter traces for all
three Tek filter sets are available at
http://www.astro.gsu.edu/~thenry/SMARTS/smarts.0.9m.filters.pdf
* An SDSS ugriz 4"x4" filter set (Sloan filters, not to be
confused with our Thuan-Gunn griz set)
-------------------------EXPOSURE TIMES-------------------------------
Details about the common filters (e.g. exposure time estimates) are
available here:
http://www.astro.gsu.edu/~thenry/SMARTS/smarts.0.9m.filters.text
However, note that you can request exposure to a certain number of
peak ADU, rather than a specific exposure time. Exposure times will,
of course, depend on seeing and cloud cover, and also on how recently
the primary mirror of the 0.9m was cleaned.
The 0.9m can take exposures as short as 0.5 seconds, but shutter
effects (uneven illumination) are a concern up to 5 seconds. It is
recommended to request defocusing or an ND filter if targets saturate
in less than 5 seconds.
Tests of astrometric (not photometric) stability show best results for
exposures longer than 60 seconds. Tracking at the 0.9m is usually
stable for up to 300 seconds. For longer exposures the observer will
typically use the autoguider.
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K N O W N I S S U E S A T T H E 0 . 9 M
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HEADERS --- The "new" TCS installed in 2005 cannot communicate with
the ARCON data acquisition computer, and as such several header fields
(including RA, DEC and EPOCH) are now garbage. Many attempts to solve
this problem have been unsuccessful. Given the actual pointing
accuracy (see below), a first step would be to use the input J2000
coordinates instead. For details, see
http://www.astro.gsu.edu/~thenry/SMARTS/smarts.0.9m.tcs
POINTING --- pointing is typically good to 20 arcseconds, which means
it is reliable enough that you should be able to use the J2000
coordinates of your intended field center. However, we HIGHLY
recommend that you provide an electronic finder (with orientation and
scale labels!) on a working website for every target.
BAD COLUMNS --- Like many CCDs, the Tek 2k CCD on the 0.9m has bad
columns. These can be avoided. Similarly, in quad-readout mode, each
quadrant is bordered by overscan regions that can be avoided.
PHANTOM OF THE 0.9M --- occasionally, the dome will spin 360 degrees
seemingly without cause. Many tests have been done to determine the
cause, and no convincing gotcha has been found.
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P L A N N I N G O B S E R V A T I O N S
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Attached to this email is the sample template (ASCII format). YOU
MUST USE THIS TEMPLATE FOR YOUR OBSERVATIONS. IT HAS A LABEL OF 2012A
AT THE TOP. The closer you adhere to the format, the smoother your
observations will go.
A few tips and requests, because we at the 0.9m like to under-promise
and over-deliver:
* No non-sidereal programs in service mode. The timing and instrument
changes make this better suited to user mode. If you must track a
moving target, do it with many short exposures.
* No polarimetry programs in service mode. As this is a non-standard
instrument setup for the 0.9m, it is better handled as user time.
* Assume you are proposing for automated observing. None of us are
familiar with your program, so everything you need must be spelled
out.
* You may only have TWO possible programs (photometric, nonphotometric
backup) per night, and each must be entirely self-contained. A
single program that can be done in either case (ignoring standard
star observations if nonphotometric, for example) is also fine.
* Include links to finder charts, with the target labeled and some
idea of the image scale and orientation. If you do not, we have no
way to spot any pointing errors.
* Assume your program will be set in stone once started. We do not
have the facility to change target lists for night #2 based on what
was observed on night #1.
* If there are time-sensitive observations that would happen during a
scheduled break, the one-hour break can be moved (but not REmoved).
* Assume the observer is going to go straight down your list as the
night progresses. Use the priority system to make sure the observer
knows which targets can be skipped if time is short.
* For best results when requesting absolute photometry, use an airmass
calculator (such as
http://www.briancasey.org/artifacts/astro/airmass.cgi)
to determine the exact times (UT) you want your standards observed,
and list each visit as a separate observation.
* The weather at CTIO is worst in winter. Programs scheduled for
December or January (Chilean summer) can likely expect to get more
than 70% photometric nights, but the odds of photometric weather in
August are low.
* Plan for overhead, as detailed for service mode at:
http://www.astro.gsu.edu/~thenry/SMARTS/smarts.overheads
* Keep it simple. Our observers are Chilean CTIO employees. They are
not scientists, nor is English their first language, and neither
Mr. Riedel nor Ms. Winters want to reword parts of your program to
make it clearer for them.
The following requests work well:
* integrating for a certain amount of time
* integrating to X number of peak counts on a target object (marked on
a finder)
* observing a target continuously for an entire night/ until UT time X
* dithering between observations (this goes for sky flats as well)
* moving the target off the center of a quad-readout frame
* explicit timing of observations (put UT times in the notes)
* listing objects, such as standard stars, multiple times if you want
them observed at different airmasses
* "use ND filter if (object) saturates in less than X seconds"
* "observations may begin in twilight"
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W H A T Y O U N E E D T O D O N O W
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Once you have read this message, please email Mr. Riedel at
riedel@chara.gsu.edu and you will be placed on the "confirmed" list
for observations in 2012A.
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If there are any further questions about anything in this email, feel
free to contact Mr. Riedel, Ms. Winters, or Dr. Henry.
Clear Skies,
Adric Riedel
SMARTS Fellow
Graduate Student, Georgia State University
Jennifer Winters
SMARTS Fellow
Graduate Student, Georgia State University
Dr. Todd J. Henry
Director, RECONS
Professor of Astronomy, Georgia State University