2MASS Image Inventory Service Help

The 2MASS Image Inventory Service allows users to rapidly find lists of 2MASS Image sets covering a specific region, position, or target object.

The service can search for both Atlas and Quicklook image sets - each "Quicklook" image corresponds to a 2MASS Atlas Image that has been lossy-compressed with hcompress, using scale = 4.0 and quant = 1.0 parameters. The Quicklook Images delivered by this service are restored from the lossy-compressed files in FITS format with full WCS information contained in the image headers. These images are suitable for position measurements, finding charts and visual inspection of the near-infrared sky.

There are two image inventory modes provided by the Inventory Service:

  1. Search for Images which overlap or cover or are enclosed by a Region
  2. Search for Images covering a Position or Object

Each mode is described in more detail below.

For a description of the image meta-data tables produced by this service, please visit the 2MASS Image Meta-Data Table Help webpage.

Finally, note that inventory service query results contain a concise data tag which can be used to re-run a query. Publishing data tags in journal articles provides readers with the means to locate and access the data the article is based on. See these instructions for further details.

CAUTION:

Always use 2MASS Atlas Images for photometric measurements -
2MASS Quicklook Images are restored from lossy-compressed files.

Search for Images overlapping or covering or enclosed by a Region

Description

This image inventory mode first finds all of the 2MASS Image sets which overlap or cover or are enclosed by the region with the specified center and diameter.

Then, the borders of these image sets are overlayed on an IRAS ISSA plate covering the specified region, creating a visual map. Finally, meta-data for each image is retrieved and tabulated.

  • A 2MASS Image set overlaps the search region when a point P on the sky exists such that P is contained in both the image set and search region.
  • A 2MASS Image set covers the search region if it contains every point in the search region.
  • A 2MASS Image set is enclosed by the search region if every point in the image set is contained in the search region.

The result page generated by the inventory service allows you to retrieve all of the FITS images found using the 2MASS Batch Image Service.

If you wish to retrieve only a subset of the images found, you can do this by downloading the ASCII meta-data table for the images, deleting the rows corresponding to those images you do not wish to retrieve, and then using the edited table as an input to the coadd_key list retrieval mode of the 2MASS Batch Image Service.

Query Inputs
Region Center

This input field must contain either a sky coordinate or an object name resolveable via IRSA, NED, or SIMBAD (2MASS object names are resolved by IRSA, all other names are resolved via NED/ SIMBAD). This coordinate or object name corresponds to the center of the region to be searched for 2MASS Image sets.

If the input field contains a string which can be interpreted as a coordinate representation, it is used as such: both decimal degree and sexagesimal notations are supported. If not, the string is sent first to IRSA, then to NED, and finally to SIMBAD to attempt name resolution. The range of acceptable name formats is set by those projects.

Examples:

  • m83
  • NGC 7479
  • 2MASXJ23045666+1219223
  • 17h 44m 34s -27d 59m 13s Equatorial J2000
  • 23h04m56.63s 12d19m22.7s Equ J2000
  • 17h44m34s -27d59m13s
  • 00h42m44.3s +41d16m08s b1950
  • 00:42:44.3 -41:16:08
  • 00 42 44.3 -41 16 08 b1983
  • 004244.3 -411608
  • 17h -27d Equ J2000
  • 17h -27d
  • 34.5565 54.2321 gal
  • 34. 54. ecl
Region Diameter

This input field must be set to the diameter (in degrees) of the region to be searched for 2MASS Image sets.

The minimum allowed diameter is 0.05 degrees, and the maximum is 7.0 degrees. Values which do not fall into this range will automatically be clamped to lie in [0.05, 7.0].

Date

This input field is used to optionally specify the observation date of image sets to be included in the inventory. All image sets in the search region with an observation date not matching the specified one will be excluded from the list of 2MASS Image sets returned.

The date format used is strict: you must specify exactly 6 numeric characters corresponding to a date in yymmdd format (yy: last 2 digits of the observation year, mm: integer month, dd: integer day).

Examples :

  • August 4, 1997 : 970804
  • August 4, 2000 : 000804
  • August 4, 2001 : 010804
  • January 4, 2001 : 010104
  • February 4, 2001 : 010204
  • February 5, 2001 : 010205

Although the 2MASS Image Service verifies the date format before it attempts to find images, the service will not check to see if there were any 2MASS observations on the specified date. If you enter a date on which no data was taken (or an erroneous scan or image number), the service will simply notify you that it was unable to find any image sets matching your retrieval criteria.

Hemisphere

This input field is used to optionally specify the observatory hemisphere of image sets to be included in the inventory. All image sets in the search region with an observatory hemisphere not matching the specified one will be excluded from the list of 2MASS Image sets returned.

The observatory hemisphere of a 2MASS Image set is the hemisphere of the 2MASS observatory where the image was taken. There are only two possible values: north (Mt. Hopkins), and south (Cerro Tololo).

Scan

This input field is used to optionally specify the nightly scan number of image sets to be included in the inventory. All image sets in the search region with a nightly scan number not matching the specified one will be excluded from the list of 2MASS Image sets returned.

The value of this input field must be an integer between 1 and 999 (inclusive).

Image

This input field is used to optionally specify the image number of image sets to be included in the inventory. All image sets in the search region with an image number not matching the specified one will be excluded from the list of 2MASS Image sets returned.

The value of this input field must be a positive integer.

Band

This option allows you to specify the 2MASS band(s) of images to include in the inventory.

  • J: Selecting this option will cause only J-band images to be included.
  • H: Selecting this option will cause only H-band images to be included.
  • Ks: Selecting this option will cause only Ks-band images to be included.
  • All: Selecting this option will cause images for all three bands to be included.

CAUTION:

Always use 2MASS Atlas Images for photometric measurements -
2MASS Quicklook Images are restored from lossy-compressed files.

Search for Images covering a Position or Object

Description

This image inventory mode first finds all of the 2MASS Image sets covering the specified position or object.

Then, the borders of these image sets are overlayed on an IRAS ISSA plate covering the specified position, creating a visual map. Finally, meta-data for each image is retrieved and tabulated.

The result page generated by the inventory service allows you to retrieve all of the FITS images found using the 2MASS Batch Image Service.

If you wish to retrieve only a subset of the images found, you can do this by downloading the ASCII meta-data table for the images, deleting the rows corresponding to those images you do not wish to retrieve, and then using the edited table as an input to the coadd_key list retrieval mode of the 2MASS Batch Image Service.

Query Inputs
Coordinates or Object Name

This input field must contain either a sky coordinate or an object name resolveable via IRSA, NED, or SIMBAD (2MASS object names are resolved by IRSA, all other names are resolved via NED/ SIMBAD). This coordinate or object name corresponds to the position to be searched for 2MASS Image sets.

If the input field contains a string which can be interpreted as a coordinate representation, it is used as such: both decimal degree and sexagesimal notations are supported. If not, the string is sent first to IRSA, then to NED, and finally to SIMBAD to attempt name resolution. The range of acceptable name formats is set by those projects.

Examples :

  • m83
  • NGC 7479
  • 2MASXJ23045666+1219223
  • 17h 44m 34s -27d 59m 13s Equatorial J2000
  • 23h04m56.63s 12d19m22.7s Equ J2000
  • 17h44m34s -27d59m13s
  • 00h42m44.3s +41d16m08s b1950
  • 00:42:44.3 -41:16:08
  • 00 42 44.3 -41 16 08 b1983
  • 004244.3 -411608
  • 17h -27d Equ J2000
  • 17h -27d
  • 34.5565 54.2321 gal
  • 34. 54. ecl
Date

This input field is used to optionally specify the observation date of image sets to be included in the inventory. All image sets covering the search position with an observation date not matching the specified one will be excluded from the list of 2MASS Image sets returned.

The date format used is strict: you must specify exactly 6 numeric characters corresponding to a date in yymmdd format (yy: last 2 digits of the observation year, mm: integer month, dd: integer day).

Examples :

  • August 4, 1997 : 970804
  • August 4, 2000 : 000804
  • August 4, 2001 : 010804
  • January 4, 2001 : 010104
  • February 4, 2001 : 010204
  • February 5, 2001 : 010205

Although the 2MASS Image Service verifies the date format before it attempts to find images, the service will not check to see if there were any 2MASS observations on the specified date. If you enter a date on which no data was taken (or an erroneous scan or image number), the service will simply notify you that it was unable to find any image sets matching your retrieval criteria.

Hemisphere

This input field is used to optionally specify the observatory hemisphere of image sets to be included in the inventory. All image sets covering the search position with an observatory hemisphere not matching the specified one will be excluded from the list of 2MASS Image sets returned.

The observatory hemisphere of a 2MASS Image set is the hemisphere of the 2MASS observatory where the image set was taken. There are only two possible values: north (Mt. Hopkins), and south (Cerro Tololo).

Scan

This input field is used to optionally specify the nightly scan number of image sets to be included in the inventory. All image sets covering the search position with a nightly scan number not matching the given one will be excluded from the list of 2MASS Image sets returned.

The value of this input field must be an integer between 1 and 999 (inclusive).

Image

This input field is used to optionally specify the image number of image sets to be included in the inventory. All image sets covering the search position with an image number not matching the specified one will be excluded from the list of 2MASS Image sets returned.

The value of this input field must be a positive integer.

Band

This option allows you to specify the 2MASS band(s) of images to include in the inventory.

  • J: Selecting this option will cause only J-band images to be included.
  • H: Selecting this option will cause only H-band images to be included.
  • Ks: Selecting this option will cause only Ks-band images to be included.
  • All: Selecting this option will cause images for all three bands to be included.

CAUTION:

Always use 2MASS Atlas Images for photometric measurements -
2MASS Quicklook Images are restored from lossy-compressed files.