Guide for Solar System Observers

Contents:
+Searching for Solar System Objects (SSOs) at IRSA
+Three Kinds of IRSA SSO searches
+Other Services of Interest
+Spitzer
+WISE and NEOWISE
+Moving Object Search Tool (MOST)
+PTF
+Getting More Help
+Quick Start Example


Searching for Solar System Objects (SSOs) at IRSA

Jump to Quick Start Example

Observations at IRSA are stored by mission and separated into images and catalogs, usually photometry catalogs. Each mission is different in its Solar System search capabilities. The latest IRSA tools allow interactive exploration of images and catalogs together, which is powerful when deciding whether or not to download data.

Three Kinds of IRSA SSO searches

Pointed observations
For missions with pointed observations (as opposed to all-sky surveys), there may have been observations targeted at a known SSO. You can search the targets by object name or NAIF ID number (Spitzer).
Precovery
For observations serendipitously obtained of a moving object, some missions allow the use of the orbital elements and the known times of the observations to figure out whether a SSO was observed. They can provide the images or photometry at the expected locations. This is no guarantee that the nearest object was the object of interest. If the ephemeris is poorly known, or if non-gravitational effects are important, as is the case for some comets, this search can fail. (For images: Spitzer, WISE/NEOWISE, PTF, 2MASS. For photometry: WISE/NEOWISE.)
Known Objects
Some missions identified moving objects known at the time of data processing, whether previously known objects or new discoveries. For 2MASS, there were ~12,000 objects identified. As of the 2014 WISE processing, there were ~700,000 objects. For WISE/NEOWISE, lists are searchable online as described below under WISE and NEOWISE. Note there are two products, a "Known Objects List" and "Moving Object Tracklets", with the latter being the more reliable. There are tables for 2MASS Known Moving Objects and IRAS Asteroid and Comet Survey (IRAS, 2MASS, WISE).
Data Set
(linked if discussed here)
Pointed
observation
search
Precovery
search
(images unless noted)
Known
object search
Spitzeryesyesno
WISE/NEOWISEnoyes (also photometry)yes
PTFnoyesno
2MASSnoyestables (see above)
IRASnonotables (see above)


Other Services of Interest

There are other tools at IRSA that are of more general interest to Solar System Observers. Finder Chart is one of them.

Finder Chart gives you simultaneous access to POSS (DSS), SDSS, 2MASS, WISE (AllWISE), and IRAS (IRIS) data and catalogs. These are all survey missions (and FinderChart is not accessing the individual exposures), so there is no SSO search per se. However, this tool is good for examining fields where your object is, or was, or will be. It provides images up to 1 degree.

Online help is available via the blue "Help" tab at the top of the results, or via the circled question marks scattered throughout the tool. The anatomy of the results screen is described in detail there and in the corresponding YouTube tutorials, or just click around and watch what changes. As for the other tools with a similar look-and-feel, you are interacting with the FITS images directly and can overlay and interact with catalogs, from IRSA or elsewhere.


Spitzer

The main Spitzer page at IRSA presents an overview of the mission, as well as documentation. Spitzer is a pointed observatory, so both pointed and precovery (for images) searches can be conducted.

The Spitzer Heritage Archive (SHA) provides a way to search the observations interactively. Upon loading, the types of searches are given on the left. To find SSO observations, do any of the following (in order of options on the left of the SHA window):

Menu optionDescriptionExample
"abstract text" Use this to find programs whose abstracts include a given string. Click on the program's name to load the observations into the browser window.Try: "Zodi".
"AORKEY"Use this to find a specific observation (e.g., as listed in a journal article reporting on the results of that observation).Try: "4890624" to find spectroscopy of 3200 Phaethon.
"Moving Object" Use this to find observations intentionally tracking on a specific SSO. You can enter the target name and it will obtain the NAIF ID for you. Try: "67P". It retrieves observations despite the original observers using different strings for the target name.
"precovery"Use this to find intentional or serendipitous observations of a given SSO. You can enter the target name and it will obtain the NAIF ID for you. Caution: time baselines covering the entire mission will take a long time! If possible, limit the range to a year or so. Try: "2004 RG179" = NAIF ID 2220663, between 2004-08-01 and 2005-01-01.
"observer"Use this to find all observations obtained by a given person. Try: "mainzer". It helps you auto-complete to a name understood by the database.
"program"Use this to find all observations obtained under a given program id (most likely included in the journal article reporting on results). Try: "collision" to find a program on asteroid collisions.

Online help is available via the blue "Help" tab at the top of the results, or via the circled question marks scattered throughout the tool. The anatomy of the results screen is described in detail there and in the corresponding YouTube tutorials, or just click around and watch what changes. When it displays images, you can interact directly with the real FITS file. For example, you can display catalogs on an image by clicking the blue "Catalogs" tab at the top of any result page.

Catalogs with Spitzer data specifically can be searched via the IRSA Catalog Search service, though they are not "moving-object enabled". Spitzer has many catalogs available; see the documentation at the main Spitzer page at IRSA.

WISE and NEOWISE

WISE is the Wide-field Infrared Survey Explorer. The main WISE/NEOWISE page at IRSA has an overview of the mission and properties (and documentation). WISE and NEOWISE are both survey missions, and as such, there are no pointed observations. Both precovery and known object searches can be conducted in WISE data.

There are several movies collected in the WISE and Solar System Objects playlist that provide several examples of how to use WISE products.

ToolDescriptionExample
WISE Image Service, "Solar System Object/Orbit" search (on left) This is a good place to start because you can search all the images from all deliveries at once. Enter the object name or ephemeris information. Select the desired image sets and bands at the bottom. Online help is available via the blue "Help" tab. Try: "Pallas". This is "precovery". (This is the Quick Start example A above.)
WISE Image Service, Catalog search (blue tab near top) [first example] After you do an image search, you can do a generic catalog search. You need to search each catalog separately. Moving objects (SSOs) may be present if a "single-exposure" catalog is chosen. Try: NEOWISE Reactivation database, NEOWISE-R Single Exposure (L1b) Source Table. It will overlay that catalog on the returned images. (Online help is available via the blue "Help" tab.)
WISE Image Service, Catalog search (blue tab near top) [second example] After you do an image search, you can do a search of a known Solar System Object Possible Association List. There is a separate version of this catalog for each mission phase. (Caution: see Note 2 below.) Try: NEOWISE Reactivation database, NEOWISE-R Known Solar System Object Possible Association List. It will overlay that catalog on the returned images.
IRSA Catalog Search [first example] Search a single-exposure catalog (without interactive image service above); search each delivery separately. (See Note 1 below)Try: WISE All-Sky Single Exposure (L1b) Source Table. This is "precovery". (This is the Quick Start example B above.)
IRSA Catalog Search [second example] Search the Known Object catalogs (without interactive image service above); search each delivery separately. (Caution: see Note 2 below)Try: "NEOWISE-R Known Solar System Object Possible Association List", All Sky Search, scroll down to the sql box and type "objid like '%Themis'".
WISE/NEOWISE Coadder Enables you to co-add images of any moving target. There is online help and YouTube videos on this service.Try: Moving Object/Stacking, "Ada" as the object name.

NOTES:

(1) WISE/NEOWISE searches can be a little confusing because of the different mission phases, see the "Mission Characteristics" section of the main WISE/NEOWISE page. For a Solar-System search, one needs to search a "single-exposure" catalog. Some people want to do a moving object search with the "AllWISE" release, which encompassses all of the WISE data taken between the beginning of the mission and when the spacecraft was initially put into hibernation in Feb 2011. But this isn't possible as AllWISE has only co-adds of the available data and SSOs are effectively removed. Look for the "single-exposure" catalogs in WISE All-Sky, NEOWISE-R, etc.(NB: WISE All-Sky covered most of the sky at sufficient depth for photometry but see the description of WISE All-Sky sky coverage).

(2) The "Known Objects" lists for WISE/NEOWISE: The online product is the "Known Solar System Object Possible Association List", one for each mission phase. This is a pipeline flag of a possible association of a source with a moving object known at the time. The identifications and photometry are not foolproof. Read the caveats in the NEOWISE explanatory supplement here . The associations may be confused with background objects, so it pays to use the WISE Image Service to interactively explore the individual frames and be sure your object is isolated from background objects. A more reliable listing of SSO identifications, developed by the WISE team, is obtained by using Moving Object Tracklets available at the Minor Planet Center. This method is a little more involved and is described here . These locations and times have been vetted, and thus are not decoyed by background objects.

WISE Catalog Searches via Command-line

You can script WISE catalog cone searches using a command-line call, sometimes labeled an Application Program Interface (API). See Moving Object API.

Moving Object Search Tool (MOST)

The Moving Object Search Tool (MOST) provides direct access to the ephemeris-generating and data search tool that is operating "under the hood" here at IRSA and elsewhere (e.g., some Planetary Data System (PDS) services). The main use case is to find serendipitous earlier observations of a newly discovered moving target, e.g., precovery searches. It lacks the visualization tools of, e.g. Spitzer and WISE, so use the services linked above for those, but it does show the object tracklets. For 2MASS, MOST is required. It will identify the specific data frames of interest, but you have to download the data and do the photometry yourself.

MOST currently knows about data from WISE and NEOWISE, Spitzer, PTF, and 2MASS. We expect to add other data sets in time.

PTF

PTF is the Palomar Transient Factory. The main PTF page at IRSA has an overview of the survey and its properties (and pointers to documentation). PTF is, from the SSO perspective, effectively a survey mission that does not cover the whole sky. As such, there are no pointed observations. Precovery searches can be conducted.

ToolDescriptionExample
PTF Image Service, "Solar System Object/Orbit" search (on left) Provides interactive access to images and catalogs. Enter the object name or ephemeris information. Long time baselines can take a long time to search!Try: Pallas
PTF Image Service catalogsPTF catalogs can be searched from the search page of the Image Service. The full frame-by-frame photometry catalog is not available independently in the IRSA Catalog Service.

Catalogs should be retrieved when searching on "Pallas" in the prior example.

Online help is available via the blue "Help" tab at the top of the results, or via the circled question marks scattered throughout the tool. The anatomy of the results screen is described in detail there, or just click around and watch what changes. When it displays images, you can interact directly with the real FITS file.

Getting More Help


Quick Start Example

What images and photometry of asteroid "Pallas" are available at IRSA?

IRSA has many datasets that might contain observations of Pallas. Each will need to be searched separately. Below is the procedure for searching the WISE and NEOWISE missions.

  1. Images
    1. Go to the WISE Image Service
    2. Click Solar System Object/Orbit
    3. Type object name "Pallas"
    4. Select all Image Sets
    5. Search
      The service will calculate an ephemeris for Pallas. The predicted positions are marked on the single-exposure frames, which you can download.

  2. Photometry
    Note: For a bright object like Pallas, known at the time of data processing, WISE/NEOWISE has photometry already tabulated. Read more below at WISE and NEOWISE, but note the caveats about the "Known Objects" list.
    1. Go to the WISE Catalog Search
    2. For WISE, click WISE All-Sky Single Exposure (L1b) Source Table and Select at top
    3. Click Moving Object Search
    4. Type Single Object Search name "Pallas"
    5. Run Query
      The service will calculate an ephemeris for Pallas. The table will show all objects found within the search radius of the predicted position. See above WISE and NEOWISE, and notes about "Precovery".


Version 1.4 (2/2/17)