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"

10364 results found.

  1. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  2. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  3. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  4. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  5. GRB 250117A: GECAM observation of a short burst
  6. Konus-Wind detection of GRB 250116A
  7. GRB 250116A: GECAM-B detection of a long burst
  8. GRB 250116A: Fermi-LAT detection
  9. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  10. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  11. Konus-Wind detection of GRB 250113A
  12. IPN triangulation of GRB 250113A
  13. GRB 250114A: Swift-XRT refined Analysis
  14. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  15. GRB 250114A: Swift detection of a burst with an optical counterpart
  16. GRB 250101A: Terskol Zeiss-2000 optical observations
  17. GRB 250106A: Swift-XRT afterglow detection
  18. Fermi trigger No 758442826: Global MASTER-Net observations report
  19. EP250108a / AT 2025kg: LCO optical observations
  20. EP250111a: Global MASTER-Net observations report
  21. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  22. EP250111a: a new X-ray transient detected by Einstein Probe
  23. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  24. Konus-Wind detection of GRB 250107C
  25. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  26. Konus-Wind detection of GRB 250107D (short/hard)
  27. IPN triangulation of GRB 250107D (short/hard)
  28. EP250109a: EP-WXT detection of an X-ray transient
  29. EP250108a: EP-WXT detection of an X-ray transient
  30. GRB 250108B: Swift-XRT refined Analysis
  31. Swift GRB 250108B: Global MASTER-Net observations report
  32. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  33. GRB 250103A: Swift-XRT afterglow detection
  34. GRB 250108B: Swift detection of a burst
  35. GRB 241228B: Fermi-LAT detection
  36. GRB 250101A: J band upper limit by SYSU 80cm telescope
  37. The EP-WXT trigger 01709129925 is likely a flaring star
  38. Fermi trigger No 757753930: Global MASTER-Net observations report
  39. GRB 250103B: Swift-XRT refined Analysis
  40. GRB 250103A: Bassano Bresciano Observatory upper limit
  41. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  42. IceCube Alert 250102.58: Global MASTER-Net observations report
  43. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  44. GRB 250103A: SVOM detection of a long burst
  45. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  46. GRB 250101A: further SAO RAS optical observations
  47. GRB 250101A: SAO RAS optical observations
  48. Swift GRB250101.56: Global MASTER-Net observations report
  49. GRB 241217a/EP241217b: ATCA Radio Detection
  50. EP241217a: VLA Radio Detection

  51. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  52. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  53. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  54. GRB 241229A: EP-FXT X-ray afterglow confirmation
  55. EP241217A: J band upper limit by SYSU 80cm telescope
  56. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  57. Konus-Wind detection of GRB 241228A
  58. EP240702a: 7DT Optical upper limits
  59. GRB 240606B: 7DT Optical upper limits
  60. GRB 241228B: Swift-XRT afterglow detection
  61. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  62. Fermi GRB 241228B: Global MASTER-Net observations report
  63. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  64. GRB 241228A: Swift-XRT refined Analysis
  65. GRB 241228A: Swift detection of a burst
  66. GRB 241217A/EP241217b: continued SOAR observations
  67. Fermi GRB 241226A: Global MASTER-Net observations report
  68. Fermi trigger No 756678579: Global MASTER-Net observations report
  69. IceCube Alert 241224.30: Global MASTER-Net observations report
  70. EP241223a: Global MASTER-Net observations report
  71. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  72. GRB241113A: 7DT Optical upper limits
  73. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  74. Fermi GRB 241223A: Global MASTER-Net observations report
  75. GRB 241223A: GOTO optical observations summary
  76. EP241217a: e-MERLIN radio observations
  77. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  78. Fermi trigger No 756447119: Global MASTER-Net observations report
  79. GRB 241217A/EP241217b: SOAR afterglow detection
  80. EP241217a: Liverpool Telescope optical upper limit
  81. GRB 241218A: Mondy AZT-33IK optical upper limit
  82. Konus-Wind detection of GRB 241204A (short/hard)
  83. EP 241217a: NIR detection with P200/WIRC
  84. GRB 241217A / EP241217b: NOT optical upper limits
  85. GRB 241218A: Swift-XRT refined Analysis
  86. EP241119a: 7DT Optical upper limits
  87. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  88. EP241217a: Global MASTER-Net observations report
  89. GRB 241218A: Swift detection of a burst
  90. EP241217a: Swift-XRT Detection
  91. EP241217a: EP detection of an X-ray transient
  92. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  93. Konus-Wind detection of GRB 241213A (EP 241213a)
  94. The EP-WXT trigger 01709128948 is likely a flaring star
  95. GRB 241215A: A long GRB detected by INTEGRAL
  96. GRB 241213A: Swift-XRT refined Analysis
  97. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
  98. GRB 241213B: MAXI/GSC detection
  99. GRB 241213A: Swift detection of a burst
  100. GRB 241209B: Mondy AZT-33IK and AbAO AS-32 optical observations

Advanced

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