Skip to main content
Circulars over Kafka event name backfill. 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"

24607 results found.

  1. EP241217a: optical upper limit with the Liverpool Telescope
  2. GRB 241209B: EP-FXT afterglow detection
  3. GRB 241218A: NOT optical upper limits
  4. GRB 241218A: Swift-BAT refined analysis
  5. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  6. EP 241217a: NIR detection with P200/WIRC
  7. EP 241217a: Possible J-band detection with WINTER
  8. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  9. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  10. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  11. GRB 241217A / EP241217b: NOT optical upper limits
  12. GRB 241218A: REM optical upper limit
  13. GRB 241217A/EP241217b: REM optical/NIR upper limits
  14. EP241217a: REM optical/NIR upper limits
  15. GRB 241217a: Liverpool Telescope optical follow-up
  16. EP241217a: Liverpool Telescope optical follow-up
  17. GRB 241218A: Swift-XRT refined Analysis
  18. EP241217a: NOT optical observations
  19. EP241217a: GROWTH-India Telescope optical observations
  20. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  21. EP241119a: 7DT Optical upper limits
  22. EP241217a: Xinglong optical follow-up observations
  23. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  24. GRB 241218A: LCOGT Optical Upper Limit
  25. GRB 241218A: Enhanced Swift-XRT position
  26. GRB 241217A: GMG Optical Upper Limit
  27. GRB 241218A: Swift detection of a burst
  28. GRB 241217A : SVOM/VT optical afterglow detection
  29. GRB 241217A: Swift-XRT afterglow detection
  30. GRB 241217A: LCO optical upper limit
  31. GRB 241217A: GRANDMA/TAROT optical upperlimits
  32. EP241217a: Swift-XRT Detection
  33. EP241217A: Non-detection from Fermi-GBM Observations
  34. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  35. EP241217a: Kinder optical follow-up observations
  36. EP241217A: LCO optical observations
  37. EP241217a: Gemini-North detection of the likely optical counterpart
  38. EP241217a: EP detection of an X-ray transient
  39. EP241107a: VLA Radio Observation
  40. GRB 241213A: Swift-BAT refined analysis
  41. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  42. GRB 241215A: Mondy AZT-33IK optical observations
  43. GRB 241212A: Swift-XRT observations
  44. GRB 241215A: Nanshan/HMT optical upper limit
  45. GRB 241215A: Montarrenti Observatory optical upper limit
  46. GRB 241215A: GROWTH-India telescope optical upper limit
  47. GRB 241215A: A long GRB detected by INTEGRAL
  48. Integral GRB241215.58: Global MASTER-Net observations report
  49. GRB 241213B: Swift-XRT observations
  50. GRB 241213A: Swift/UVOT Upper Limits
  51. GRB 241213A: Swift-XRT refined Analysis
  52. GRB 241212A: Fermi GBM detection
  53. EP241208a: NOT optical upper limits
  54. GRB 241213A: LCOGT Optical Upper Limits
  55. GRB 241213B: MAXI/GSC detection
  56. EP241213a: EP detection of An X-ray Transient
  57. GRB 241213A: REM optical/NIR upper limits
  58. GRB 241213A: Enhanced Swift-XRT position
  59. GRB241212A: OHP/T193 optical observations
  60. GRB 241213A: SAO RAS optical upper limit
  61. LIGO/Virgo/KAGRA S241210fu: Updated Sky localization
  62. GRB 241213A: Swift detection of a burst
  63. GRB 241212A : SVOM/C-GFT optical upper limit at early phase
  64. GRB 241212A: AstroSat CZTI detection
  65. GRB 241209B: GRANDMA/TRT upper limit
  66. GRB 241207A: TSHAO Zeiss-1000 optical observations
  67. GRB 241212A: SVOM detection of a bright long burst
  68. GRB 241207A: EIRSAT-1 GMOD Detection
  69. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  70. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  71. GRB 241129A: Fermi GBM Observation
  72. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  73. GRB 241209D: REM optical/NIR upper limits
  74. GRB 241209B: Swift-XRT afterglow detection
  75. GRB 241209C: Fermi GBM Observation
  76. GRB 241209A: Swift-XRT refined Analysis
  77. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  78. EP241208a: Optical upper limit with Kinder observations
  79. GRB 241209B: SVOM/VT afterglow detection
  80. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  82. GRB 241207B: Fermi GBM Observation
  83. GRB 241209D: Swift-XRT refined Analysis
  84. GRB 241209D: Fermi GBM Observation
  85. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  86. GRB 241209D: COLIBRÍ detection of the afterglow
  87. GRB 241209A: COLIBRÍ Optical Upper Limit
  88. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  89. GRB 241209A: GRANDMA/TAROT upper limit
  90. GRB 241209A: REM optical/NIR observations
  91. GRB 241209D: Enhanced Swift-XRT position
  92. GRB 241209D: Swift detection of a burst
  93. GRB 241209A: Enhanced Swift-XRT position
  94. GRB 241114B: cubesat Avion detection
  95. GRB 241209A: VLT optical observations
  96. GRB 241209A: GOTO optical upper limits
  97. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  98. EP241208a: EP detection of a fast X-ray transient
  99. GRB 241209A: Swift detection of a short burst
  100. Fermi GRB 241207B: Global MASTER-Net observations report

Advanced

Download all Circulars as a .tar.gz archive:
Looking for U.S. government information and services? Visit USA.gov