Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

20832 results found.

  1. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  2. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  3. GRB 240910A: further Swift observations and confirmation of afterglow
  4. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  5. EP240918a: JinShan optical upper limits
  6. EP240918a: Optical upper limits with Kinder observations
  7. EP240918a: GMG Optical Upper Limit
  8. EP240918a: an X-ray transient detected by Einstein Probe
  9. GRB 240916A: NOT optical observation
  10. IPN triangulation of GRB 240913C / EP 240913a
  11. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  12. GRB 240821A: radio observation with the VLA
  13. GRB 240916A: Swift-XRT afterglow detection
  14. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  16. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  17. EP240913a: VLT/HAWK-I near-infrared upper limits
  18. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  20. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  21. GRB 240914A: Swift-XRT observations
  22. GRB 240910A: SVOM/VT optical observations
  23. EP240913a: NOT optical upper limits
  24. EP240913a: JinShan optical upper limits
  25. EP240913a: ESO-NTT optical observations
  26. GRB 240914A: ESO-NTT optical observations
  27. GRB 240905E: further NOT optical observations
  28. EP240913a: EP-WXT detection of a fast X-ray transient
  29. GRB 240911A: LCO optical observations
  30. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  31. GRB 240912A: Swift/UVOT Detection
  32. GRB 240911A: Swift-XRT observations
  33. GRB 240912A: J-band observations with WINTER
  34. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  35. GRB 240912A: Enhanced Swift-XRT position
  36. GRB 240912A: Redshift from OSIRIS+/GTC
  37. Fast X-ray Transient EP240801a: GMRT radio observations
  38. GRB 240910A: Redshift from OSIRIS+/GTC
  39. GRB 240912A: Swift detection of a burst with an optical counterpart
  40. GRB 240910A: JinShan optical observations
  41. IPN triangulation of GRB 240905B (short)
  42. GRB 240825A: 7DT Optical Upper Limit
  43. GRB 240905E: SVOM/VT optical observations
  44. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  45. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  46. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  47. GRB 240910A: SVOM/GRM observation
  48. EP240908a: Mondy and AbAO follow-up observations
  49. EP240908a: TRT optical upper limit
  50. EP240908a: EP detection of a fast X-ray transient
  51. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  54. GRB 240905E: GIT optical upper limit
  55. GRB 240905B: Swift-XRT observations
  56. GRB 240905E: Gaoyazi/GOT optical upper limits
  57. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  58. GRB 240905B: Fermi-LAT detection
  59. GRB 240905E: J-band observations with WINTER
  60. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  61. GRB 240905E: AKO Optical Upper Limit
  62. GRB 240905E: SVOM/C-GFT optical upper limit
  63. GRB 240905E: OHP/MISTRAL T193 optical upper limit
  64. GRB 240905E: NOT optical upper limits
  65. GRB 240905E: REM optical/NIR upper limits
  66. GRB 240902B: AstroSat CZTI detection of a long burst
  67. GRB 240905E: LCOGT Optical Upper Limit
  68. GRB 240905E: Swift/UVOT Upper Limits
  69. GRB 240905E: SAO RAS optical upper limit
  70. GRB 240905E: Nanshan/HMT optical upper limit
  71. GRB 240905E: Swift detection of a burst
  72. GRB 240819A: Optical upper limits from TESS
  73. GRB 240904A: Swift detection of a burst
  74. LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
  75. GRB 240825A: MeerLICHT afterglow detection
  76. GRB 240828A: SAO RAS AS-500(2) optical observations
  77. GRB 240825A: TSHAO Optical Upper Limit
  78. GRB240828B: REM optical/NIR upper limits
  79. GRB 240828B: AbAO optical upper limit
  80. GRB 240825A: SOAR observations
  81. GRB 240828B: Mephisto optical upper limit
  82. GRB 240828B: GRANDMA Optical Upper Limit
  83. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  84. LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
  85. GRB 240825A: MeerKAT detection
  86. GRB 240828B: J-band upper limit from WINTER
  87. GRB 240828B: GMG Optical Upper Limit
  88. GRB 240828B: SVOM/C-GFT optical upper limit
  89. GRB 240828B: SAO RAS optical upper limit
  90. GRB 240828A: SAO RAS optical observations
  91. GRB 240629A: First GRB Detected by BurstCube
  92. GRB 240828A: KAIT Optical Afterglow Candidate
  93. GRB 240825A: SVOM/VT optical detection
  94. GRB 240828A: Swift-XRT afterglow detection
  95. GRB 240825A: further SAO RAS optical observations
  96. GRB 240825A: iTelescope optical observations
  97. GRB 240828B: Swift-XRT afterglow detection
  98. GRB 240829A: Swift detection of a burst
  99. GRB 240828A: AstroSat CZTI detection of a long burst
  100. Fermi GRB 240828A: Bassano Bresciano Observatory upper limit

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov