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.

Lucene Examples (click to copy):

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

19139 results found.

  1. GRB 250129A: LCO optical observations
  2. GRB 250129A: NOT optical observations and redshift confirmation
  3. GRB 250129A: GOTO optical observations show brightening afterglow
  4. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  5. Swift GRB 250129A: Global MASTER-Net observations report
  6. Fermi GRB 250128B: Global MASTER-Net observations report
  7. GRB 250128B: GOTO optical upper limit
  8. Swift GRB 250128B: Global MASTER-Net observations report
  9. EP250125a: Upper limits from Swift/BAT-GUANO
  10. GRB 250128B: LCO optical observations
  11. GRB 250127A: Swift-XRT observations
  12. GRB 250127B: DDOTI Upper Limit on the Afterglow
  13. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  14. Fermi GRB 250128A: Global MASTER-Net observations report
  15. Fermi GRB 250127B: Global MASTER-Net observations report
  16. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  17. GRB 250127A: SVOM/VT upper limit
  18. GRB 250127A: Swift ToO observations
  19. GRB 250127A: LCO optical upper limit
  20. EP250125A: Non-detection from Fermi-GBM Observations
  21. EP250125a: Optical upper limit with Kinder observations
  22. EP250125a: REM optical counterpart detection
  23. EP250125a: Swift/XRT detection of a fading counterpart
  24. EP250125a: a new X-ray transient detected by Einstein Probe
  25. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  26. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  27. EP250108a: AbAO, CMO and Terskol optical upper limits
  28. GRB 250121A: INTEGRAL/SPI-ACS detection
  29. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  30. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  31. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  32. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  33. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  34. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  35. ATCA detection of possible radio counterpart to GRB 250114A
  36. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  37. GRB 250119B: INTEGRAL/SPI-ACS detection
  38. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  39. EP 250108A: Late-time optical observation by LCO
  40. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  41. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  42. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  43. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  44. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  45. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  46. GRB 250117A: GECAM observation of a short burst
  47. EP250108a / AT2025kg: GMG Optical Observations
  48. EP250108a / AT2025kg: VLA radio upper limit
  49. GRB 241217A / EP241217B: radio detection with the VLA
  50. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  51. GRB 250114B: Swift-XRT afterglow detection
  52. GRB 250114B: SVOM/VT upper limit
  53. EP250108a: MeerKAT radio upper limit
  54. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  55. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  56. GRB 250114B: Liverpool Telescope optical upper limit
  57. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  58. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  59. GRB 250114B: Swift-XRT observations
  60. GRB 250114A: LCO optical counterpart detection.
  61. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  62. Integral GRB250114.55: Global MASTER-Net observations report
  63. GRB 250114A: LCOGT optical afterglow i-band detection
  64. GRB 250114B: Swift ToO observations
  65. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  66. GRB 250113A: INTEGRAL/SPI-ACS detection
  67. GRB 250114A: REM detection of the optical and NIR counterpart
  68. GRB 250114A: LCO optical observations
  69. GRB 250114A: TRT optical observations
  70. Swift GRB 250114A: Global MASTER-Net observations report
  71. GRB 250101A: Terskol Zeiss-2000 optical observations
  72. EP250108a / AT 2025kg: SAO RAS optical observations
  73. EP241021a: SMA radio observation
  74. EP250109b: optical upper limits with the Liverpool Telescope
  75. GRB 250106A: Swift-XRT afterglow detection
  76. Fermi trigger No 758442826: Global MASTER-Net observations report
  77. EP250111a: KAIT optical observations
  78. GRB 250109A / EP250109a: Mephisto optical upper limits
  79. EP250108a: Mephisto detection
  80. EP250111a: Mondy optical observation
  81. EP250108a / AT 2025kg: LCO optical observations
  82. EP250111a: Global MASTER-Net observations report
  83. EP250108a / AT 2025kg: Swift UVOT detections
  84. EP250108a: optical follow-up observations with the Liverpool Telescope
  85. EP250111a: NOT likely optical counterpart
  86. EP250111a: a new X-ray transient detected by Einstein Probe
  87. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  88. EP250108a: further NOT optical observations
  89. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  90. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  91. GRB 250108A: Swift/XRT afterglow fading
  92. EP-WXT trigger EP250108a:Xinglong optical follow-up observations
  93. GRB 250101A: CMO RC-500 optical observations
  94. EP250108a: NOT optical observations
  95. EP-WXT trigger EP250109a:Xinglong optical follow-up observations
  96. EP250109a: Swift/UVOT non-detection
  97. EP250108a: Liverpool Telescope likely optical counterpart
  98. GRB 250108B: Gemini-North likely redshift z = 2.197
  99. GRB 250108B: 1.3m DFOT upper limit
  100. GRB 250108B: REM optical/NIR upper limits

Advanced

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