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MAST Spectral/Image Scrapbook Help


Help Index:

Introduction
Input Parameters
Spectrum Output
Image Output
Thumbnails and Links

Please see also:

How we made the scrapbook


Introduction

The MAST Spectral/Image Scrapbook is designed to allow users to take a quick look at sample data in the MAST archive of a particular astronomical object of interest. It is particularly useful if the user is not already familiar with the datasets involved. The spectral mission included in the scrapbook are:
  • HST/FOS
  • HST/GHRS
  • HST/STIS
  • Astro/HUT
  • Astro/WUPPE
  • IUE
  • EUVE
  • ORFEUS/TUES
  • ORFEUS/BEFS
  • FUSE

The imaging missions included in the scrapbook are:

  • HST/ACS
  • HST/WFPC2
  • HST/STIS
  • HST/FOC
  • Astro/UIT

The tool utilizes a pair catalogs of representative spectra and images compiled from the MAST archive. Each of the tables lists unique datasets representing either each object or unique pointing observed by each MAST mission/instrument. These datasets contain either a calibrated spectrum or image, as the case may be. More than one dataset may be listed for an assortment of bandpasses, depending on the instrument. For instance, two GHRS spectra are included in the catalog for the star T Tauri, one for the long-wavelength and one for the short-wavelength ultraviolet ranges, among the 13 GHRS spectra in the archive. For IUE, representative images of an object are included for both low and high dispersion if they exist. For WFPC2 images only, one 2.5 x 2.5 arcmin U, B, V, R, and I image is included per pointing when available; a band centered on an emission line is also included when available. In addition, the table lists the names of the object returned by SIMBAD and NED, if available, and the name and coordinates of the object as given in the original observing catalog.

The user may query the table in one of several ways (see Search Criteria listed below):

  • Enter an object name to be resolved by SIMBAD or NED, and use the SIMBAD/NED coordinates to search the catalog for any entries within a specified radius of that position.
  • Enter a set of coordinates to search the catalog by position.
  • Enter an object name to be resolved by SIMBAD or NED, and search the catalog for entries with that resolved name.
  • Enter the mission target name to search by object name as catalogued by that mission (may include "%" as a wildcard).

Note that the individual spectra or images in the catalog are typical, not always the best quality available, and are intended to convey the general attributes and quality of the data. To explore further the data available, the user should proceed to the catalog search page for the relevant mission.

For extended objects, some missions obtained data from multiple pointings around the object. In this case for spectra, data from only a single pointing may be displayed (example: the Orion nebula). No attempt has been made to provide a listing of the various pointings for such objects.

Solar system objects are not included in this tool. A special solar system scrapbook tool is under consideration.



Input Parameters

This section describes the options available on the scrapbook search form. Only the target name or position is required; the remaining fields will default to the values shown.

Target
Enter the name or the coordinates of the astronomical object of interest.
  • If you specify the name to be resolved for the "Coordinates" or "Resolved Target Name" search, use standard nomenclature as utilized by SIMBAD or NED for best results.
  • For the "Mission Target Name" search mode only, a "%" can be used as a wildcard and all names are converted to upper-case; e.g., entering "r136%" will return all entries in which the mission object name begins with R136.
  • To specify coordinates, enter J2000 RA and DEC as decimal degrees or as hours, minutes, and seconds. Several formats will be recognized as coordinates:
         - decimal degrees e.g. 65.4975 19.535 or 65.4975, +19.535
         - hours minutes seconds e.g. 4 21 59.4, 19 32 6 or 4 21 59.4 19 32 6
         - hours minutes, deg minutes e.g. 4 21 19 32 or 4 21, 19 32

Data Type
The user specifiies a request for spectral or image data (but not both). By default, spectral data will be displayed.

Search Criteria
Determines how the query of the catalog of representative spectra or images is performed. Three search options are currently available:
  • Coordinates - Searching the TORS/TORI tables by coordinates within the defined search radius is the default search option. Users may enter their own coordinates (consult examples under "Target"), or use the SIMBAD/NED name resolvers to obtain coordinates. The software uses the resolvers automatically when characters are entered as part of the target name. SIMBAD is the default resolver. As an example, if one enters "NGC4151" for the target, then selects "coordinates" for the search criteria and "SIMBAD" for the name resolver, the scrapbook program uses SIMBAD to determine the coordinates for NGC4151, calculates a circular search area of specified radius centered on the returned coordinates, returns all entries from either Table of Representative Spectra or Images (depending which Data Type is selected) which fall within this area, and displays the spectra or images.
  • Resolved Target Name - This mode compares the target name returned by SIMBAD or NED to the resolved names stored in the Table of Representative Spectra or Images. This mode is useful when looking for specific targets in crowded fields or for large extended objects, but may also miss some relevant entries. As an example of usage, if one enters "NGC 224", SIMBAD resolves the target as "M 31", and the tool returns entries from the table with the SIMBAD Name "M 31".
  • Mission Target Name - In this mode the user's input object name is compared directly to the mission object names without using a name resolver. The mission object names are those assigned by the mission and listed in its observing catalog. The names may or may not be consistent with those of other missions. This mode can be useful for targets with unusual designations or to find certain types of objects such as "jets". All input target names are converted to upper-case and a "%" may be used as a wildcard. If one enters "NGC%4151" for example, then entries matching "NGC4151" and "NGC 4151" will be returned. If one enters, "%JET", the entries ending in "JET" such as "HH46-JET" will be returned. This mode is the fastest to execute, but may return only a subset of the desired entries due to differences in the assigned mission object names. Warning: using wildcards can result in extremely large search results.

Search Radius
Enter the coordinate search radius in arcminutes. The default of 3 arcmin will work for many objects, but a smaller radius may be needed in crowded fields. A larger radius may be needed to locate a large extended object. This parameter is not used when searching by name only (see above).

Maximum thumbnails per mission
By default, a maximum of 10 thumbnails will be displayed for each mission. This value may be changed to any number greater than zero. This option affects only the display of the thumbnails. The search results table will always list all the found entries.

Name Resolver
Select either SIMBAD (the default) or NED for name resolution. If the name is not found within either database, try entering coordinates (J2000) instead of a target name. This entry applies only to "Coordinates" and "Resolved Target Name" searches with an input name.

Submit Query
Click on this button to begin the query. The Table of Representative Spectra or Representative Images will be searched for entries which meet the specified search criteria. The result may be none, one, or many objects. You may wish to redo the search with a smaller search radius in a crowded field, or using different search criteria.

Reset
Clicking reset will return the form to its default values.

Help
Clicking help will display this help file. If you still have trouble, please e-mail your question to archive@stsci.edu.



Spectrum Output

The output of your query will include a list of representative data sets for the specified object or coordinates, thumbnails of the spectra or images, and links to browse files, data, and catalog search pages. You may also select spectra to be coplotted using the Customized Plot tool.

Table Headings

Mission/Instrument
The mission and/or instrument from which the data are derived. The table entries will be linked to the appropriate MAST mission home page.

Plot
Click on the appropriate buttons to select the spectra that you would like to display together on one graph (see Customized Plot).

Dataset Name
The name of the dataset in the MAST archive. This may be a single observation or a combination of integrations, depending on the particular mission and instrument involved.

Mission Object Name
The name of the astronomical object as given in the mission catalog. Various designations were used by the different missions. Since all stored object names are upper case, all input names are converted to upper case when using the "Mission Target Name" mode.

Comments
Explanatory comments regarding the data sets. The contents will vary with mission. Currently the field describes the gratings used by GHRS spectra.

Simbad/NED Name
The name of the astronomical object as returned by SIMBAD (or NED if selected). SIMBAD (NED) is used to resolve multiple designations and to help the user determine if the MAST datasets are of the same target or of multiple targets falling within the search radius. Since some SIMBAD names contain lower case characters, input names are not converted to upper case in "Coordinates" or "Resolved Target Name" modes.

RA (2000), Dec (2000)
The right ascension and declination in J2000 epoch as listed in the Table of Representative Spectra, taken from the mission observing catalog.

Angular Separation
When performing coordinate searches, the angular separation (radius), given in arcminutes, between the SIMBAD (or NED) coordinates and the mission object coordinates listed in the Table of Representative Spectra catalog. The output entries are sorted by mission and angular separation.

Customized Plot

The customized plot option allows users to preview and rescale public spectra and light curve data archived within MAST. By default, spectra will be automatically scaled to the full range of wavelengths and light curves to the full range of times. For spectra, the default y axis plot scale runs from 0 (or .25 * the minimum flux for spectra with negative fluxes) to the 10th highest flux. For light curves, the default plot scale is from the minimum to the maximum flux value. Note the same scaling rules apply to plots of multiple data sets.

Each plot is automatically assigned a color, up to a maximum of 15. The spectra are labelled by their dataset names, with a summary of each dataset given below the plot. After inspection, you may wish to change the selection of datasets which are displayed. Use your browser "Back" button to do this.

Plot range
Adjust the minimum and maximum wavelengths (in Ångstroms) or times (in seconds), and/or the minimum and maximum fluxes (in erg/cm2/sec/Å for calibrated fluxes or e-/cadence for Kepler light curves) to select the spectral region of interest and to exclude noisy data.

Plot dimensions
Adjust the X size and Y size in pixels to create the size of plot desired. Although the default plot size is 800 x 450 pixels, the maximum dimensions allowed are 850 x 640 pixels.

Redraw plot
Use this button to replot the spectra when you have changed the plot range or plot dimensions.

Scale Factors
Each displayed plot can be scaled with respect to the other using the "Scale Factors" form elements which are labbelled by data set name. For example, setting a scale to 1.5 for one data set will cause the fluxes for that one plot to be multipled by 1.5. This can be useful for compensating for differences in exposure times.



Image Output

The output of your query will include a list of representative images for the specified object or coordinates, previews of the images, and links to browse files, data, and catalog search pages.

Table Headings

Mission/Instrument
The mission and/or instrument from which the data are derived. The table entries will be linked to the appropriate MAST mission home page.

Dataset Name
The name of the dataset in the MAST archive. This may be a single observation or a combination of integrations, depending on the particular mission and instrument involved.

Mission Object Name
The name of the astronomical object as given in the mission catalog. Various designations were used by the different missions. Since all stored object names are upper case, all input names are converted to upper case when using the "Mission Target Name" mode.

Comments
Explanatory comments regarding the data sets. The contents will vary with mission. Currently the field describes the filters and apertures used for WFPC2 image data.

Simbad/NED Name
The name of the astronomical object as returned by SIMBAD (or NED if selected). SIMBAD (NED) is used to resolve multiple designations and to help the user determine if the MAST datasets are of the same target or of multiple targets falling within the search radius. Since some SIMBAD names contain lower case characters, input names are not converted to upper case in "Coordinates" or "Resolved Target Name" mode.

RA (2000), Dec (2000)
The right ascension and declination in J2000 epoch as listed in the Table of Representative Images, taken from the mission observing catalog. For WFPC2 images these refer to the position of the V1 axis, i.e., the center of the WFPC2 field of view.

Angular Separation
When performing coordinate searches, the angular separation (radius), given in arcminutes, between the SIMBAD (or NED) coordinates and the mission coordinates listed in the Table of Representative Images catalog. The output entries are sorted by mission and pointing.



Thumbnails and Links

The thumbnails displayed are small but readable quick-look versions of the calibrated data. Descriptions of how these thumbnails were created will be included in the planned mission help pages for the scrapbook. The ACS previews do not have the optimal stretch. Viewing the preview in Aladin will permit you to see the detail in the image.

Click on the mission/instrument name to go to the mission search page to query data from the full mission catalog. The search form will be loaded with the user-specified coordinates (or those derived from NED or SIMBAD) and the user-specified search radius, but the user may modify these or any other search parameter before searching the mission catalog.

For spectra, click on the data_id entry below each thumbnail to view the standard preview page. The preview pages contain a full-sized image of the spectrum and other associated information. Clicking on the mission name above the thumbnail will take the user to a query page filled out with the target name or coordinates and ready to be submitted. This is an alternative way of accessing mission-specific data products for the object. click on the data_id entry or the thumbnail to display a full-size image.

For non-HST missions, click on the object name listed below each thumbnail to download the data (fits files bundled in tar) to your disk. For HST data, click on the object name to display exposure informatiom.

Click on "Cross Correlation Search" to search the entire MAST archive for a listing of the MAST data sets for a particular target. This will submit the user specified target name to the "xcorr" cross correlation search form. The resolver name, number of entries displayed per mission, and the search radius specified in the scrapbook search form will also be passed to xcorr.