MOST - Moving Object Search Tool Instructions

The Moving Object Search Tool (MOST) computes the orbit of a solar system object and searches for images that covered the object's predicted positions in select image archives housed by IRSA. Aids to visualization include an orbit plot and links to display the FITS images. It can serve as a "precovery" tool, determining whether newly discovered objects were previously observed.

Also available is a Program Interface to MOST.

Image Datasets and Search Parameters

MOST can query all publicly-available phases of the WISE/NEOWISE mission (select "wise_merge" under Image Dataset for all), Spitzer, PTF, ZTF, and 2MASS. If the Observation time ranges are left blank, it will use the entire length of the mission. This could be a lengthy search, so limiting the time range is usually necessary. This is especially important for WISE/NEOWISE (i.e. wise_merge to MOST) near the ecliptic poles where the coverage can be very high. When a dataset is selected, an info box will give information on the time range of the data.

Datasets marked "Internal use only" are proprietary and choosing one will give an "Internal Service Error" to non-enabled servers.

For Output Mode, the "Regular" option is recommended. The full option displays the full ephemeris and other products and requires some scrolling.

Object Input

Solar system objects can be input by name, number, designation, or NAIF ID number. Name resolution and ephemeris generation for known objects is done via query to JPL's Horizon database.

There can be name ambiguities. For example, entering "WISE" is a problem as there were many asteroids and comets discovered by the WISE mission. Entering "Neptune" is unclear as there are ephemeris files for both Neptune and the Neptune system barycenter. MOST will deliver a messsage if there is an ambiguity. The message may contain suggested NAIF ID's, e.g. "1003094:NID" for comet 317P/WISE or "899:NID" for Neptune. NAIF ID's may be input directly as well. In a few cases, there are satellites and asteroids with the same name, and you may distinguish them by, e.g. "Europa:SAT" and "Europa:AST".


Asteroid 324 Bamberga:   "Bamberga" or "324"
Periodic comet P/29 Schwassmann-Wachmann 1:   "29P" or "P/29" (but not P29)
Non-periodic comet 337P/WISE:   "C/20010 N1"
Titan:   "Titan"
Neptune:   "899:NID"

The ephemeris can also be calculated for comets or asteroids using orbital elements supplied by the user, either individually or in the Minor Planet Center (MPC) one-line format (further information). But object name/number input is best, as it will query JPL Horizons to get the osculating orbital elements closest in time to the observations.

Additional Data Requests

Clicking on Create Fits and DS9 Region Files Tarballs will pack the retrieved images and markers for the moving object (in DS9 region format) into separate tarballs. The image tarball could be quite large for a large search, so leave this option off and see how many images there will be first.


MOST streams results to the browser as it goes, so don't exit the output page until it completes.

The Regular output displays a plot of the orbital path, and a table ("Images with a Matched Object Position") with the matched images along with object parameters at the time. The table that is displayed has links to download the images individually or display them in the IRSA Viewer. However if the data have access restrictions, e.g. ZTF, this will only work for authorized users who have logged into the browser session. The display table columns are described below.

Column Key for Final Table

Column Description
Download/View Links to download or view the data.
DS9 File Markers for the moving object in DS9 "region" format.
Image ID A unique identifier for the image data, not necessarily the image file name.
date_obs Date (UTC) of the observation.
time_obs Time (UTC) of the midpoint of the observation.
mjd_obs Modified Julian Date (days) of the midpoint of the observation.
ra_obs Ephemeris prediction of the object's right ascension (deg, J2000).
dec_obs Ephemeris prediction of the object's declination (deg, J2000).
r Heliocentric distance of the object (AU).
Δ Geocentric distance of the object (AU).
dist_ctr Projected distance of the object from the center of the image (deg).
phase Sun-Object-earth angle (deg).
vmag Estimate of visual magnitude (from Horizons).

An intermediate table, available in the Full output or via a link called Image Metadata with a Matched Object Position, has the same information as the final table and additional metadata from the dataset. The keywords are described in the table below and further information can be found in these links: WISE/NEOWISE, 2MASS, PTF, ZTF, and Spitzer.

Additional Columns in "Image Metadata with a Matched Object Position" Table

Column Description
ra1, dec1, ra2, dec2 etc. Right ascension and declination of the 4 corners of the image (deg, J2000)
match match = 1 indicates a matched image (added by MOST)
crpix1, crpix2 Center of image (pixels)
crval1, crval2 Center of image (deg, J2000)
equinox Equinox of coordinates
band WISE band number; 1 (3.4 microns), 2 (4.6 microns), 3 (12 microns), 4 (22 microns)
scan_id Identification of pole-to-pole orbit scan
date_obs Date and time of mid-point of frame observation, UTC
mjd_obs Modified Julian Date of mid-point of frame observation, UTC
dtanneal Elapsed time in seconds since the last anneal
moon_sep The angular distance from the frame center to the Moon (deg)
saa_sep The angular distance from the frame center to South Atlantic Anomaly (SAA) boundary (deg)
qual_frame This integer indicates the quality score value for the Single-exposure image frameset, with values of 0 (poor quality), 5, or 10 (high quality)
image_set image_set = 4 for 4band, 3 for 3band, 2 for 2band, and 6, 7 etc. for NEOWISE-R year 1, 2 etc.
ordate UT date of reference (start of operations for the night)
hemisphere N or S hemisphere
scanno Nightly scan number
fname FITS file name
ut_date UT date of scan (YYMMDD)
ut UT time of scan (HH:MM:SS.SSS)
telname Telescope location - Hopkins or CTIO
mjd Modified Julian Date of observation
ds ds = full for 2mass
obsdate Observation UT date/time YYYY-MM-DD HH:MM:SS.SSS
obsmjd Modified Julian Date of observation
nid Night database ID
expid Exposure database ID
ccdid CCD number (0...11)
rfilename Raw-image filename
pfilename Processed-image filename
obsdate Observation UT date/time YYYY-MM-DD HH:MM:SS.SS
obsjd Julian Date of observation (days)
filefracday Observation date with fractional day YYYYMMDDdddddd
field ZTF field number
ccdid CCD number (1...16)
qid Detector quadrant ID (1...4)
rcid Readout channel ID (0...63)
fid Filter ID
filtercode Filter name (abbreviated)
pid Science product ID
nid Night ID
expid Exposure ID
itid Image type ID
imgtypecode Single letter image type code
reqkey Spitzer Astronomical Observation Request number
bcdid Post Basic Calibrated Data ID (Level 2 product search)
reqmode Spitzer Astronomical Observation Request type
wavelength Bandpass ID
minwavelength Min wavelength (microns)
maxwavelength Max wavelength (microns)
time UT time of observation
exposuretime Exposure time (sec)

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