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IMAPS Search Help
There are two types of IMAPS-1 data: raw images, and corrected, coadded images. Only the coadded files have assigned wavelengths. To download an IMAPS file, click on any of the listed image numbers for the desired target. This will display a list of links to individual files that can then be downloaded.
- Target Name
- The common name of the astronomical object.
(All the observed objects are listed in the table.)
- The name resolver you want to use, if you want to resolve an object into its coordinates. You can resolve an object name either before a search, or you can redraw the form with the resolved coordinates in place. You can also elect not to resolve the object name when doing the search, but to search the IMAPS database on the object name given.
To resolve an object name before a search, enter the object name in the Object Name field, select either NED or SIMBAD for the resolver, and hit the Search button. NED is the NASA Extragalactic Database at Caltech in Pasadena, California, and SIMBAD is the Set of Identifications, Measurements, and Bibliography for Astronomical Data at the Centre de Données astronomiques in Strasbourg, France. The object name will be sent to the chosen resolver, which will send back the coordinates. (If the object name is not recognized by the resolver, or there is some other problem with the SIMBAD or NED services, then the search form will be redrawn with an error message at the top.) These coordinates will then be used to search the IMAPS database, along with whatever other query qualifications you have given.
We recommend that you use object name resolution to find observations of specific objects in the database. This is the most reliable way to look up observations, because the observer could have given any object na me at all (for example, NGC1976 instead of M42, or PARALLEL-FIELD). However, if you do know the object name that the observer used, you can select Don't resolve, in which case the object name will not be resolved into coordinates, but will be used as a search qualification in the database. (This will happen only when you press the Search button.)
The SIMBAD and NED object name resolvers can resolve only fixed objects; they cannot compute the positions of moving objects (planets, comets, etc.). To find moving objects, try selecting the appropriate object class, entering an object name that could match what you're looking for, and selecting Don't resolve for the name resolver. NED is an extragalactic database, and generally won't resolve object names within the Milky Way galaxy.
- The Right Ascension and Declination around which you want to search. A number of formats are accepted for the RA and Dec. Here are some examples:
Decimal Degrees 185.63325 29.8959861111111 Hours, minutes and Seconds 12 22 31.98 29 53 45.55 12h22m31.98s 29d53m45.55s 12:22:31.98 +29:53:45.55 12h22'31.98" 29d53'45.55" 12h 22m 31.98s 29d 53m 45.55s 12h 22' 31.98" 29d 53' 45.55" 12h 22' 31.98" -29d 53' 45.55" 12h22'31".98 -29d53'45".55 12h22m31s.98 -29o53m45s.55 12h 22' 31".98 -29d 53' 45".55 Hours/Degrees and Minutes (no seconds) 12 22 29 53 12h22m +29d53m 12h22m 29d53m 12:22m 29:53m 12h22' 29d53' 12h 22m 29d 53m 12h 22' 29d 53' 12h 22' -29d 53' The RA may be given in decimal degrees by indicating a D or d after the degrees: 12d 22m 29d 53mSpacing is not important, as long as the value is unambiguous, and that you can delimit the hours/degrees, minutes, and (optional) seconds with letters, colons, spaces, or any character that's not a digit or a decimal point.Note also that seconds of the form 31".98 or 31s.98 are accepted. This should make it easy to cut and paste values into these fields from electronic publications.
- The radius of the search box around the RA and Dec, in floating-point arcminutes (e.g., 5.0).
This used to be the "radius" of a coordinate box, but we now compute the angular separation between each r esult dataset and the search center, so this really is a radius. (The results will be sorted on the angul ar separation by default.) So this really is a circular radius around the search position. One result is t hat you can do fancy stuff like searching for all observations between 2 and 8 arcminutes from the center of a galaxy (just give 2 .. 8 for the radius).
- The equinox of the RA and Dec you have entered, either B1950 or J2000. This only affects the input coordinates; there is a separate selector for the equinox of the output coordinates.
If you hit the Resolve button to get an object's coordinates and redraw the form, the equinox will be set to J2000, since that's the equinox of the coordinates returned by the object name resolvers.
- The IMAPS image number (or exposure sequence number) listed in the table and contained in the file names, desribes the order in which the IMAPS observations were obtained. Exposure numbers ran from 0000 to 0721, however the first 79 were test exposures and not archived. The IMAPS-2 sequnce numbers will begin where IMAPS-1 left off.
With IMAPS-1, a series of observations were usually taken of a particular star. The series would usually include 2-4 exposures from each of the 4 echelle positions, plus a background exposure which involved leaving the aperture open and the telescope pointed toward the object but turning off the high voltage. Exposures within these series taken at the same echelle position were possible candidates for coadding.
- The average start date and time, in GMT, for the coadded images, based on the observation start dates calculated for the raw image files. Since the coadded exposures were usually taken consecutively, the observing times generally differ by only a few minutes.
- The start date and time, in GMT, for the particular IMAPS image. These times were determined by subtracting the exposure times from the observation end times recorded in the IMAPS-1 exposure log.
- This entry describes either the position of the echelle grating (a number from 1 to 4) or whether a background exposure was obtained (a value of "B"). Each grating position covers 1/4 of each echelle order, so a series of four exposure is needed to cover the entire echelle spectrum.
- The Henry Draper catalog number.
- The assigned file name. The raw data sets file names use the naming convention imaps1_0nnn.fits where nnn is the 3-digit exposure sequence number assigned by Princeton Observatory describing the order in which targets were observed (i.e., the first archived observation is imaps1_0079.fits and the last target is imaps1_0721.fits. Clicking on the raw file name in the IMAPS-1 finding list table will download the selected raw data FITS file.
The coadded scan file names are defined as imaps1_nnn-mmm.fits where nnn is the first coadded observation number and mmm is the last.
- You may now search on any column in the mission database. Select the field you wish to search on and type in the qualification. You may find the valid range of values by clicking on the field name. NOTE that if you choose a field in BOTH the form and in the User Option field, then you may not get results or the result you expect.
- You may choose the columns to be displayed in the output. A set of columns that are commonly requested has been chosen as a default.
The default set of columns is:
Mark File Name Target Name RA (J2000) Dec (J2000) Obs Start Time Category (Object Class) Exp Time Angular Separation (')You remove output columns by highlighting the column to be removed and then clicking on the remove button to the right of the list of chosen output columns.
You may determine the order of column placement by highlighting a column and then clicking on the up or down buttons to the right of the list of chosen output columns.
You may add a column to the list of chosen columns. Select the desired column on the pull down menu beneath the list of chosen output columns. Then click on the add button. The column will be added to the bottom of the output column list.
- Choose how you want the output rows sorted. You can select up to three fields to sort on. The rows will be sorted in the order of the first sort field; if two rows have the same sort field, they will be sorted in order of the second sort field, and so on.
For each field, you can select that the rows be sorted in reverse order on that field by selecting the reverse checkbox. For example, you can sort the rows with the most recent observations first by selecting Observation Date for the first sort field and selecting the reverse checkbox next to it.
- Some queries will be capable of returning thousands of rows or more. such large search results tend to use up memory on both the client and server sides, and aren't usually useful. By default, we limit the number of rows displayed to 100 rows, but you can increase (or decrease) this limit as needed.
- Just what you'd think: the equinox of the coordinates displayed in the output.
- Select this checkbox if you want to see the SQL query that the IMAPS Search engine constructs from your query qualifications. The query will be shown at the end of the search results.
SQL (Standard Query Language, pronounced either "ess cue ell" or "sequel") is a language used used by most relational database systems for retrieving information from database tables. The IMAPS Search Page takes your search specifications and converts them to an SQL query to run on our database. Viewing the generated query is often useful for debugging, and may also be useful for SQL-literate users who want to see what logic was used in the query. (In fact, this may be useful for most people, since SQL is pretty easy to understand.)
- Select this checkbox if you want to have a set of distinct rows displayed. This is useful if you would like to see a distinct list of objects with certain criteria e.g. all the objects within an object class. To make this function useful, you should not select column names such as Data Id, Mark or Observation Date in as output columns as all output is considered when making row s distinct.
- You may choose one of three display options: HTML Form, a comma separated list, and Excel spreadsheet
- The name resolver you want to use, if you want to resolve an object into its coordinates. You can resolve an object name either before a search, or you can redraw the form with the resolved coordinates in place. You can also elect not to resolve the object name when doing the search, but to search the IMAPS database on the object name given.
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