0.9-m Welcome & Overview

  1. Contact People
  2. Scheduling
  3. Instrumentation
  4. Known issues at the 0.9-m
  5. Planning Observations
  6. What you need to do now

Hello, SMARTS, Chilean, and NOAO users!                

If you have recently been awarded time on the 0.9-m, you will soon be contacted by 0.9-m coordinator Adric Riedel with detailed instructions on how to proceed.  Here, we describe the preparation process (in fact, is almost verbatim from the e-mail you will receive) to ensure you obtain the best possible data for your project.  If you are preparing a proposal for the 0.9-m, this website provides information that will best inform you of the capabilities and limitations of the two observing modes (user and service).  In either case, this website will hopefully help with your preparations. 

C O N T A C T   P E O P L E

The responsible authorities for the SMARTS 0.9m are:

Mr. Adric Riedel (GSU), SMARTS Fellow for the 0.9m.

Dr. Todd Henry (GSU), SMARTS 0.9m Coordinator.

Dr. Charles Bailyn (Yale), Director of the SMARTS Consortium.

Questions about 0.9m operations should be directed to Mr. Riedel 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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Time on the SMARTS 0.9m is a mix of classical observing and service observing, divided into (generally) alternating seven night blocks the CTIO staff call 'turnos'.  Within each 'turno', time is assigned by the night (or half-night, but not less).  As such, we cannot guarantee weather conditions.

The observing schedule for the 0.9-m is posted (and updated) here:

Under the 'TIMES' link for your night, you will also find a listing of precisely what hours you have been given. This will aid in planning your programs.

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, who will send you a template 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 will also need to fill out the instrument form at


(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 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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Pictures of the instrument can be found here

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 depth and a FOV of 13.69' on the sky, 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 10 years, and has been incredibly stable, both photometrically and astrometrically.

More detailed information about the following points may be found here:

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.

There are also three available gain settings:

      1: (unavailable, failed in March 2009)
      2: Read Noise ~ 1.6 ADU = 3.9 e-
      3: Read Noise ~ 1.8 ADU = 3.2 e-
      4: Read Noise ~ 2.6 ADU = 2.7 e-

Finally, 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):

CTIO also has some old 2"x2" filters useable in the 0.9m, listed here:


Their use is not recommended --- many of them are seriously degraded and all of them vignette on the 0.9m in FULL chip mode.

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.


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

* An SDSS ugriz 4"x4" filter set (Sloan filters, not to be confused with our Thuan-Gunn griz set) Details about the common filters (e.g. exposure time estimates) are available here:


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K N O W N   I S S U E S   A T   T H E   0 . 9 M

HEADERS --- there is a known issue with the headers.  The "new" TCS installed in 2005 does not properly communicate with the ARCON data acquisition computer, and as such several header keywords have meaningless values.  We are continuing to work on this long-term problem, but do not yet have a solution.  For details, see


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.

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.  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.  Otherwise, a bad pixel mask (unbinned - simply rename to exclude '.txt') can be used to interpolate across the columns.

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P L A N N I N G   O B S E R V A T I O N S

A sample observation list template (ASCII format) can be found here.  YOU MUST USE THE TEMPLATE FOR YOUR OBSERVATIONS.  You will be contacted by the 0.9m coordinator with a template appropriate for the current observing semester.  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.

* 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 non-photometric, for example) is also fine.

* 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.

* 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


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:

* Keep it simple.  Our observers are Chilean CTIO employees.  They are not scientists, nor is English their first language, and Mr. Riedel does not 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)

* 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"

* observing a target continuously for an entire night/ until UT time X

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W H A T   Y O U   N E E D   T O   D O   N O W

Anticipate an email from Mr. Riedel, perhaps begin compiling the necessary information as outlined in this page, and promptly respond with the requested information.  You will then be placed on the "confirmed" list for observations in the upcoming semester.


If there are any further questions about anything in this email, feel free to contact Mr. Riedel or Dr. Henry.

Clear Skies,

Adric Riedel
Graduate Student, Georgia State University

Dr. Todd J. Henry
Director, RECONS
Professor of Astronomy, Georgia State University

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