Reference library · Astronomical world · Observation & imaging
Astronomy & astrophotography
An astronomical image becomes a scientific observation when its target, sky position, exact time, observer location, optical train, detector, exposure, calibration and processing are retained. The resources here identify fixed and moving objects, test coordinates and epochs, compare measurements and connect an image to calibrated archive data. A catalogue lookup, plate solution and astrophysical interpretation are separate claims, and the page keeps them separate.
A successful plate solve establishes a coordinate mapping, not the physical identity or nature of every source in the frame. Catalogue matches depend on epoch, proper motion, resolution and selection effects; transient names and preliminary orbits can change. Photometry and spectroscopy require calibrated methods beyond visual resemblance. Retain WCS residuals, catalogue and release identifiers, time standard, instrument metadata, raw and calibration frames and processing history, and state when an object remains a candidate.
Before you reach for an atlas
Record the characters first.
Matching a photograph against a memory is how misidentifications happen. Working through
these in order gives you a description that someone else can check — and that stays
useful even if the determination later changes.
Exact time and place
Record exposure start and duration, time standard, clock source, observer coordinates and elevation.
UTC, local civil time, Julian Date and barycentric corrections are not interchangeable. Moving objects, transients and time series can be unusable when the clock or observing centre is ambiguous.
Target and sky coordinates
Record target designation, coordinate frame, epoch or equinox, field centre, orientation and plate scale.
Preserve the WCS solution and residuals. Use stable catalogue identifiers because common names and coordinates can refer to different components or epochs.
Optical train and detector
Record telescope, aperture, focal length, reducer or barlow, mount, guider, camera, binning and filters.
Include detector temperature and gain or ISO where relevant. An equipment name alone does not define the sampling, spectral response or field of view.
Acquisition and calibration
Record every exposure, cadence, dither and the bias, dark, flat, comparison-star or wavelength calibration used.
Keep raw science and calibration frames. Stacked output without its constituent exposures and rejection settings cannot be independently checked.
Separate presentation edits from quantitative processing. Record uncertainties, comparison stars, catalogue release and any rejected data rather than publishing only the polished image.
These are the observations. Standards covers the vocabularies
that carry them into a record — including Darwin Core for biological occurrences,
REMBI and OME for imaging, and ABCD-EFG for geological material — while each observation
profile records its own method-specific context. Prepare a
contribution covers what to keep alongside the files themselves.
Resources
Grouped by the question you are asking.
A resource can appear under more than one heading. Each entry states who maintains it,
what it is best for, and where it stops being reliable.
Nothing here matches that.
Clear the filter, or search the whole library from the library index.
Compare against reference evidence
Atlases, catalogues and reference collections for comparing an unknown with documented material or measurements.
Centre de Données astronomiques de Strasbourg, Strasbourg Observatory
Position and field searching across published astronomical catalogues, with catalogue documentation, tables and machine-access formats.
Best for
Cross-matching a field or source against the specific catalogue appropriate to the measurement and retaining its release and ReadMe.
Limits
Catalogues have different epochs, selection functions, uncertainties and quality flags. Coverage is not exhaustive and source-catalogue reuse terms vary.
Coverage
Global astronomical catalogues across wavelengths and object types.
Reuse
Reuse terms are set by each source catalogue; cite the catalogue and VizieR record.
An interactive sky atlas for survey imagery, SIMBAD and VizieR overlays, catalogue cross-matching and local FITS/WCS inspection.
Best for
Visually checking a solved field against survey imagery and catalogue sources while retaining their identifiers.
Limits
HiPS layers are often resampled visualisations rather than original calibrated files. Authority and reuse conditions remain with each upstream archive.
Coverage
All-sky and targeted survey layers and catalogues supplied through CDS and partner archives.
Reuse
Aladin Desktop and Lite software are GPLv3; displayed data retain provider terms.
European Space Agency Science Archives Team and Gaia Data Processing and Analysis Consortium
The reference archive for Gaia positions, proper motions, parallaxes, broad-band photometry, variability and released spectra.
Best for
Checking astrometric identity and epoch-dependent position against a named Gaia data release.
Limits
Crowding, zero-points, selection effects and release-specific source identifiers matter. The live archive warned of instability during DR4 preparation at the last check.
Coverage
All-sky stellar and other source data within Gaia's observing and processing limits.
Reuse
Gaia data are publicly accessible; cite the applicable release and follow ESA and Gaia acknowledgement guidance.
Contributing
Public access is available without payment; registration is optional but recommended for sustained or saved queries.
A long-baseline archive of visual and instrumental variable-star photometry with bandpass, uncertainty and observer provenance.
Best for
Comparing a time series with historical observations and inspecting the filters, errors and observer metadata behind each point.
Limits
Instruments, filters and error practices are heterogeneous; visual observations have intrinsically larger scatter. Time and quality flags need careful interpretation.
Coverage
International variable-star photometry contributed by professional and amateur observers.
Reuse
AAVSO data-use and citation guidelines apply.
Contributing
Search and export are open; submission requires an account and observer code.
NASA Jet Propulsion Laboratory Solar System Dynamics Group
Observer- and time-specific ephemerides for Solar-System bodies, including coordinates, rates, light-time, visibility and frame choices.
Best for
Testing whether a moving object should have occupied the measured position at the recorded time and observing site.
Limits
Observer centre, time scale, refraction and coordinate-frame defaults must be checked. Coverage has object-specific bounds and the service is best-effort.
Coverage
Solar-System objects represented in JPL ephemeris and small-body services.
Reuse
NASA and JPL terms apply; cite Horizons and retain the query parameters and solution date.
Centre de Données astronomiques de Strasbourg, Strasbourg Observatory
The primary non-Solar-System name resolver, joining identifiers, ICRS coordinates, object types, measurements and bibliography.
Best for
Resolving alternate designations and checking coordinates, object type and literature for a fixed astronomical source.
Limits
A heterogeneous literature meta-compilation rather than a catalogue, and it excludes Solar-System objects. Measurements from different sources and epochs are not automatically comparable.
Coverage
Galactic and extragalactic objects outside the Solar System.
Reuse
SIMBAD database content is ODbL; linked measurements and publications retain source terms.
Centre de Données astronomiques de Strasbourg, Strasbourg Observatory
Position and field searching across published astronomical catalogues, with catalogue documentation, tables and machine-access formats.
Best for
Cross-matching a field or source against the specific catalogue appropriate to the measurement and retaining its release and ReadMe.
Limits
Catalogues have different epochs, selection functions, uncertainties and quality flags. Coverage is not exhaustive and source-catalogue reuse terms vary.
Coverage
Global astronomical catalogues across wavelengths and object types.
Reuse
Reuse terms are set by each source catalogue; cite the catalogue and VizieR record.
An interactive sky atlas for survey imagery, SIMBAD and VizieR overlays, catalogue cross-matching and local FITS/WCS inspection.
Best for
Visually checking a solved field against survey imagery and catalogue sources while retaining their identifiers.
Limits
HiPS layers are often resampled visualisations rather than original calibrated files. Authority and reuse conditions remain with each upstream archive.
Coverage
All-sky and targeted survey layers and catalogues supplied through CDS and partner archives.
Reuse
Aladin Desktop and Lite software are GPLv3; displayed data retain provider terms.
European Space Agency Science Archives Team and Gaia Data Processing and Analysis Consortium
The reference archive for Gaia positions, proper motions, parallaxes, broad-band photometry, variability and released spectra.
Best for
Checking astrometric identity and epoch-dependent position against a named Gaia data release.
Limits
Crowding, zero-points, selection effects and release-specific source identifiers matter. The live archive warned of instability during DR4 preparation at the last check.
Coverage
All-sky stellar and other source data within Gaia's observing and processing limits.
Reuse
Gaia data are publicly accessible; cite the applicable release and follow ESA and Gaia acknowledgement guidance.
Contributing
Public access is available without payment; registration is optional but recommended for sustained or saved queries.
A cross-identification and synthesis service for galaxies, quasars and other extragalactic objects, including redshifts, distances, spectral energy distributions and literature.
Best for
Resolving an extragalactic source and tracing the measurements and publications behind its identifiers and redshift.
Limits
Extragalactic only and updated in releases rather than continuously. Legacy APIs cannot see data ingested after January 2026; use the current APIs.
Coverage
Extragalactic objects and associated measurements and literature.
Reuse
No blanket open licence is stated; cite NED and the original data sources.
A moderated living index of variable-star identities, coordinates, AUIDs, variability types, periods, magnitude ranges and references.
Best for
Checking a variable-star designation and the current classification and period evidence attached to it.
Limits
An index rather than a light-curve archive or formal publication. Crowded fields, blends and incomplete literature can remain, and records are revised.
Coverage
Known and candidate variable stars worldwide.
Reuse
AAVSO citation and data-use guidance apply.
Contributing
Public search is open; an AAVSO account is required for submissions and revisions.
Smithsonian Astrophysical Observatory under the International Astronomical Union
The official clearing house for designations, astrometric observations, orbital records and circulars for minor planets, comets and outer natural satellites.
Best for
Checking an official designation and the observation and orbit record for a Solar-System small body.
Limits
Preliminary designations and orbits evolve as observations arrive. A short arc or catalogue entry does not prove a secure identification.
Coverage
Minor planets, comets and outer natural satellites.
Reuse
No blanket database licence is stated; use MPC citation and data-use guidance.
Contributing
Public access is open; astrometric submission uses MPC and ADES workflows and usually requires an observatory code.
NASA Jet Propulsion Laboratory Solar System Dynamics Group
Observer- and time-specific ephemerides for Solar-System bodies, including coordinates, rates, light-time, visibility and frame choices.
Best for
Testing whether a moving object should have occupied the measured position at the recorded time and observing site.
Limits
Observer centre, time scale, refraction and coordinate-frame defaults must be checked. Coverage has object-specific bounds and the service is best-effort.
Coverage
Solar-System objects represented in JPL ephemeris and small-body services.
Reuse
NASA and JPL terms apply; cite Horizons and retain the query parameters and solution date.
Weizmann Institute of Science under the International Astronomical Union supernova and transient framework
The official IAU mechanism for reporting and naming astronomical transients, with discovery and classification reports, coordinates, photometry and spectra.
Best for
Checking whether a transient has an official designation and whether it is merely reported, classified or confirmed.
Limits
A named candidate is not necessarily classified or confirmed. Proprietary periods exist and the service discourages bulk scraping of search pages.
Coverage
Reported extragalactic and other astronomical transients within TNS scope.
Reuse
TNS and source-report terms apply; cite the discovery and classification reports used.
Contributing
Public search is open; reporting requires an approved account or group, and API automation requires bot credentials.
Astrometry.net team; web service hosted through Canadian astronomy data infrastructure
A blind plate-solving service that identifies an unknown star field and returns standards-based WCS metadata and object annotations.
Best for
Turning an astrophotograph with no reliable coordinates into a testable sky position and plate solution.
Limits
The shared queue has no solve guarantee; sparse, distorted or poor-signal fields can fail. WCS still needs residual validation and is not photometric calibration.
Coverage
Stellar fields that can be matched to the service's index files.
Reuse
Anonymous uploads are public and default to CC BY 3.0; sign in to control visibility and licensing. The software distribution is GPLv3 overall.
Contributing
Anonymous solving is available, but private or sensitive images should be uploaded only through an account with visibility set deliberately.
Check image privacy before uploading: the anonymous path is public. A plate solution should be retained with scale, rotation, parity and residuals rather than copied as a target name only.
Software or tool Open Research pass ·
Use the right method
Published field, preparation, imaging, measurement and analysis methods, with their limitations and safety requirements.
A long-baseline archive of visual and instrumental variable-star photometry with bandpass, uncertainty and observer provenance.
Best for
Comparing a time series with historical observations and inspecting the filters, errors and observer metadata behind each point.
Limits
Instruments, filters and error practices are heterogeneous; visual observations have intrinsically larger scatter. Time and quality flags need careful interpretation.
Coverage
International variable-star photometry contributed by professional and amateur observers.
Reuse
AAVSO data-use and citation guidelines apply.
Contributing
Search and export are open; submission requires an account and observer code.
Astrometry.net team; web service hosted through Canadian astronomy data infrastructure
A blind plate-solving service that identifies an unknown star field and returns standards-based WCS metadata and object annotations.
Best for
Turning an astrophotograph with no reliable coordinates into a testable sky position and plate solution.
Limits
The shared queue has no solve guarantee; sparse, distorted or poor-signal fields can fail. WCS still needs residual validation and is not photometric calibration.
Coverage
Stellar fields that can be matched to the service's index files.
Reuse
Anonymous uploads are public and default to CC BY 3.0; sign in to control visibility and licensing. The software distribution is GPLv3 overall.
Contributing
Anonymous solving is available, but private or sensitive images should be uploaded only through an account with visibility set deliberately.
Check image privacy before uploading: the anonymous path is public. A plate solution should be retained with scale, rotation, parity and residuals rather than copied as a target name only.
Software or tool Open Research pass ·
Place it in context
Occurrence, stratigraphic, catalogue and archive services that situate a record in space, time and literature.
Centre de Données astronomiques de Strasbourg, Strasbourg Observatory
The primary non-Solar-System name resolver, joining identifiers, ICRS coordinates, object types, measurements and bibliography.
Best for
Resolving alternate designations and checking coordinates, object type and literature for a fixed astronomical source.
Limits
A heterogeneous literature meta-compilation rather than a catalogue, and it excludes Solar-System objects. Measurements from different sources and epochs are not automatically comparable.
Coverage
Galactic and extragalactic objects outside the Solar System.
Reuse
SIMBAD database content is ODbL; linked measurements and publications retain source terms.
Centre de Données astronomiques de Strasbourg, Strasbourg Observatory
Position and field searching across published astronomical catalogues, with catalogue documentation, tables and machine-access formats.
Best for
Cross-matching a field or source against the specific catalogue appropriate to the measurement and retaining its release and ReadMe.
Limits
Catalogues have different epochs, selection functions, uncertainties and quality flags. Coverage is not exhaustive and source-catalogue reuse terms vary.
Coverage
Global astronomical catalogues across wavelengths and object types.
Reuse
Reuse terms are set by each source catalogue; cite the catalogue and VizieR record.
An interactive sky atlas for survey imagery, SIMBAD and VizieR overlays, catalogue cross-matching and local FITS/WCS inspection.
Best for
Visually checking a solved field against survey imagery and catalogue sources while retaining their identifiers.
Limits
HiPS layers are often resampled visualisations rather than original calibrated files. Authority and reuse conditions remain with each upstream archive.
Coverage
All-sky and targeted survey layers and catalogues supplied through CDS and partner archives.
Reuse
Aladin Desktop and Lite software are GPLv3; displayed data retain provider terms.
European Space Agency Science Archives Team and Gaia Data Processing and Analysis Consortium
The reference archive for Gaia positions, proper motions, parallaxes, broad-band photometry, variability and released spectra.
Best for
Checking astrometric identity and epoch-dependent position against a named Gaia data release.
Limits
Crowding, zero-points, selection effects and release-specific source identifiers matter. The live archive warned of instability during DR4 preparation at the last check.
Coverage
All-sky stellar and other source data within Gaia's observing and processing limits.
Reuse
Gaia data are publicly accessible; cite the applicable release and follow ESA and Gaia acknowledgement guidance.
Contributing
Public access is available without payment; registration is optional but recommended for sustained or saved queries.
A cross-identification and synthesis service for galaxies, quasars and other extragalactic objects, including redshifts, distances, spectral energy distributions and literature.
Best for
Resolving an extragalactic source and tracing the measurements and publications behind its identifiers and redshift.
Limits
Extragalactic only and updated in releases rather than continuously. Legacy APIs cannot see data ingested after January 2026; use the current APIs.
Coverage
Extragalactic objects and associated measurements and literature.
Reuse
No blanket open licence is stated; cite NED and the original data sources.
A moderated living index of variable-star identities, coordinates, AUIDs, variability types, periods, magnitude ranges and references.
Best for
Checking a variable-star designation and the current classification and period evidence attached to it.
Limits
An index rather than a light-curve archive or formal publication. Crowded fields, blends and incomplete literature can remain, and records are revised.
Coverage
Known and candidate variable stars worldwide.
Reuse
AAVSO citation and data-use guidance apply.
Contributing
Public search is open; an AAVSO account is required for submissions and revisions.
A long-baseline archive of visual and instrumental variable-star photometry with bandpass, uncertainty and observer provenance.
Best for
Comparing a time series with historical observations and inspecting the filters, errors and observer metadata behind each point.
Limits
Instruments, filters and error practices are heterogeneous; visual observations have intrinsically larger scatter. Time and quality flags need careful interpretation.
Coverage
International variable-star photometry contributed by professional and amateur observers.
Reuse
AAVSO data-use and citation guidelines apply.
Contributing
Search and export are open; submission requires an account and observer code.
Smithsonian Astrophysical Observatory under the International Astronomical Union
The official clearing house for designations, astrometric observations, orbital records and circulars for minor planets, comets and outer natural satellites.
Best for
Checking an official designation and the observation and orbit record for a Solar-System small body.
Limits
Preliminary designations and orbits evolve as observations arrive. A short arc or catalogue entry does not prove a secure identification.
Coverage
Minor planets, comets and outer natural satellites.
Reuse
No blanket database licence is stated; use MPC citation and data-use guidance.
Contributing
Public access is open; astrometric submission uses MPC and ADES workflows and usually requires an observatory code.
NASA Jet Propulsion Laboratory Solar System Dynamics Group
Observer- and time-specific ephemerides for Solar-System bodies, including coordinates, rates, light-time, visibility and frame choices.
Best for
Testing whether a moving object should have occupied the measured position at the recorded time and observing site.
Limits
Observer centre, time scale, refraction and coordinate-frame defaults must be checked. Coverage has object-specific bounds and the service is best-effort.
Coverage
Solar-System objects represented in JPL ephemeris and small-body services.
Reuse
NASA and JPL terms apply; cite Horizons and retain the query parameters and solution date.
Weizmann Institute of Science under the International Astronomical Union supernova and transient framework
The official IAU mechanism for reporting and naming astronomical transients, with discovery and classification reports, coordinates, photometry and spectra.
Best for
Checking whether a transient has an official designation and whether it is merely reported, classified or confirmed.
Limits
A named candidate is not necessarily classified or confirmed. Proprietary periods exist and the service discourages bulk scraping of search pages.
Coverage
Reported extragalactic and other astronomical transients within TNS scope.
Reuse
TNS and source-report terms apply; cite the discovery and classification reports used.
Contributing
Public search is open; reporting requires an approved account or group, and API automation requires bot credentials.
Astrometry.net team; web service hosted through Canadian astronomy data infrastructure
A blind plate-solving service that identifies an unknown star field and returns standards-based WCS metadata and object annotations.
Best for
Turning an astrophotograph with no reliable coordinates into a testable sky position and plate solution.
Limits
The shared queue has no solve guarantee; sparse, distorted or poor-signal fields can fail. WCS still needs residual validation and is not photometric calibration.
Coverage
Stellar fields that can be matched to the service's index files.
Reuse
Anonymous uploads are public and default to CC BY 3.0; sign in to control visibility and licensing. The software distribution is GPLv3 overall.
Contributing
Anonymous solving is available, but private or sensitive images should be uploaded only through an account with visibility set deliberately.
Check image privacy before uploading: the anonymous path is public. A plate solution should be retained with scale, rotation, parity and residuals rather than copied as a target name only.
Software or tool Open Research pass ·
Safety
Some observations and preparations need specialist safeguards.
Hazards change with the field, site, material and equipment. Follow the requirements of
the source method, manufacturer, facility and relevant authority, and do not improvise
a procedure whose controls or training you do not have.
Never point unfiltered optics at the Sun
Direct solar observation through a telescope, finder, binoculars, camera or improvised filter can cause immediate permanent eye injury and equipment damage. Use equipment and front-aperture filtration specifically designed and certified for solar observation, follow the manufacturer's instructions and obtain competent supervision. A photographic neutral-density filter, smoked glass or exposed film is not a solar filter.
This is orientation, not laboratory training, and it is not a substitute for the safety
instruction and supervision your institution requires.
Corrections
Know this field better than this page does?
The most valuable correction is not another link. It is knowing that an entry's stated limit
is wrong, or that a resource practitioners rely on is missing.
