Planning an Observing Run

So, you have a list of targets in mind. Before you head out to the telescope, you need to check over the list to find out which ones are suitable for your circumstances. Important factors are:

is it visible at all from your site?
is it visible at night at this time of year?
when does it rise to a decent altitude(*)?
when does it set below a decent altitude(*)?
how many "good" hours will you have during a single night?
what is the best time of night to observe it?
how large a field of view do you need?
should you use any filters? If so, which ones?
how long should each exposure be?
how many exposures will you need?
do you need just one set of pictures on a single night? Or do you need a bunch taken over some extended period on a single night? Or do you need pictures taken on several different nights?

(*) Just what counts as a decent altitude, anyway? In general, if you have the option, pick times when the airmass of your object is less than 1.5, or at most less than 2. Otherwise, your object will be blurry and faint, and your hard work may not gain you good results.

It helps to know the parameters of your instrumental system. You should know, or be able to find out, all of the following:

what is the latitude and longitude of the RIT Observatory?
how large is each telescope's aperture?
what is each telescope's focal length?
what is the QE of the cameras you might use?
how large a field of view will each camera provide on each telescope?
what are the limits on altitude and azimuth for each telescope?
what are rough limits for the brightest and faintest object visible through each telescope?

One tool that can help with some of this work is

an on-line signal-to-noise calculator for CCD photometry

There are actually several of these scattered around the WWW; some are maintained by large observatories and are specialized for use with a particular telescope or instrument.

After you have checked and double-checked your list to pick out the best objects, you should make up a finding chart for each one. On the finding chart, be sure to include such information as the name, coordinates, rough times of rise and set (for the current time of year). Indicate clearly the object(s) of interest in each field. Your chart should show the size of the field, in arcminutes, and also note the orientation: North this way, East that way.

Making an observing proposal

Large observatories have more users than telescopes (alas). In order to prevent fistfights from breaking out inside the domes, observatories create Time Allocation Committees (TACs) to divvy up telescope time to the various astronomers. The TACs base their decisions on observing proposals, which describe

a target (or associated list of targets)
the equipment needed
the time required to acquire the necessary data
constraints on lunar phase
the scientific justification

You can find examples of some observing proposals on-line:

You must create an observing proposal for this class and submit it by Thursday, Apr 13. The TAC will meet on soon thereafter to consider each proposal.

The pieces of an observing proposal

Your proposal must answer the following questions:

Who? Personnel

Who are you? What is your experience?

What and Where? Target(s)

What will you look at? What sort of thing is it? How bright is it? Make a table showing the position and magnitude of each target. Include a finding chart for each object, with the target clearly indicated.

How? Equipment

What telescope will you use? Which camera? Will you use filters? If so, which ones? What exposure times are required?

When? Times and Dates

When is the target visible? What are the earliest and lates dates within the period under consideration which satisfy your needs? Are there particular dates on which special events occur? Which moon phases are acceptable, and what constraints does that place on the dates and times?

Why? Scientific Justification

What's the point? What do you plan to learn from these observations? Explain how the images you will acquire supply the information you want to know. You should include references to other work on this or similar objects -- you might do literature searches on

You should describe the type of reductions you will perform on the images: astrometry, photometry, or something else. You should also explain any additional analysis; for example, if you are looking for variability, you should explain how you will use the light curve to determine the period and amplitude of variation.

You must be able to show that the time and equipment requested will yield images that can answer your scientific questions.

When you are ready, you can fill out the observing proposal form.

Last modified 4/13/2010 by MWR.