Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

23661 results found.

  1. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  2. GRB 250702A: GECAM-B detection
  3. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  4. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  5. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  6. GRB 250702F: REM optical afterglow detection
  7. EP250702a: Global MASTER-Net observations report
  8. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  9. GRB 250703A: Fermi GBM Final Real-time Localization
  10. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  11. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  12. Fermi GRB 250702E: Global MASTER-Net observations report
  13. Fermi GRB 250702B: Global MASTER-Net observations report
  14. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  15. Fermi GRB 250702F: Global MASTER-Net observations report
  16. Fermi GRB 250702C: Global MASTER-Net observations report
  17. Swift GRB 250702F: Global MASTER-Net observations report
  18. GRB 250702F: Fermi GBM Final Real-time Localization
  19. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  20. GRB 250702E: Fermi GBM Final Real-time Localization
  21. Konus-Wind detection of GRB 250627A
  22. IPN triangulation of GRB 250627A (short)
  23. GRB 250702A: Fermi GBM Detection
  24. GRB 250702D: Fermi GBM Final Localization Correction
  25. GRB 250702C: Fermi GBM Final Real-time Localization
  26. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  27. GRB 250702B: Fermi GBM Final Real-time Localization
  28. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  29. GRB 250702A: Fermi GBM Final Real-time Localization
  30. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  32. GRB 250628B: SVOM/VT optical upper limit
  33. GRB 250628B: EP-FXT counterpart detection
  34. LIGO/Virgo/KAGRA S250629bs: Updated Sky localization
  35. GRB 250627A: SVOM/GRM detection of a short burst
  36. LIGO/Virgo/KAGRA S250629ae: Updated Sky localization
  37. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S250628am: Updated Sky localization
  40. GRB 250628A: REM optical/NIR upper limits
  41. GRB 250628C: Fermi GBM Final Real-time Localization
  42. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  43. GRB 250628B: SVOM detection of a long burst
  44. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  45. Fermi GRB 250626A: Global MASTER-Net observations report
  46. Swift GRB 250628A: Global MASTER-Net observations report
  47. GRB 250628A: Swift detection of a burst
  48. GRB 250625A: Swift-BAT refined analysis
  49. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  50. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  51. GRB 250626A: Fermi GBM Final Real-time Localization
  52. GRB 250625A: SVOM/C-GFT upper limit in early phase
  53. GRB 250625A: GECAM-B detection
  54. GRB 250625A: ABObservatory afterglow detection
  55. GRB 250625A: Fermi-LAT detection
  56. GRB250625A: Fermi GBM Observation
  57. Swift GRB 250625A: Global MASTER-Net observations report
  58. GRB 250625A: NOT z-band upper limit
  59. GRB 250625A: SVOM/VT optical confirmation
  60. GRB 250620B: Fermi GBM Observation
  61. Fermi GRB 250625A: Global MASTER-Net observations report
  62. GRB 250625A: Swift detection of a burst
  63. GRB 250625A: Fermi GBM Final Real-time Localization
  64. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  65. Fermi GRB 250624A: Global MASTER-Net observations report
  66. GRB 250624A: Fermi GBM Final Real-time Localization
  67. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  68. Fermi GRB 250623A: Global MASTER-Net observations report
  69. GRB 250623A: Fermi GBM Final Real-time Localization
  70. GRB 250521A: VZLUSAT-2 detection
  71. GRB 250617B: Swift-BAT refined analysis
  72. Fermi trigger No 772190032: Global MASTER-Net observations report
  73. Konus-Wind detection of GRB 250620C
  74. IPN triangulation of GRB 250620C (long/bright)
  75. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  76. GRB 250620C: SVOM/GRM observation
  77. GRB 250620A: SVOM/GRM observation of a short burst
  78. GRB250620A: Fermi GBM Observation
  79. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  80. Fermi GRB 250621A: Global MASTER-Net observations report
  81. GRB 250619B: Fermi GBM Observation
  82. GRB 250621A: Fermi GBM Final Real-time Localization
  83. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  84. GRB250620C: Fermi GBM Observation
  85. GRB 250506A - SVOM/ECLAIRs Refined analysis
  86. The EP-WXT trigger 01709179071 is likely a flaring star
  87. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  88. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  89. GRB 250620C: Fermi GBM Final Real-time Localization
  90. Fermi trigger No 772128434: Global MASTER-Net observations report
  91. GRB 250620B: Fermi GBM Final Real-time Localization
  92. GRB 250620A: Fermi GBM Final Real-time Localization
  93. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  94. GRB 250617B: Nickel telescope optical observations
  95. GRB 250619B: Fermi GBM Final Real-time Localization
  96. Fermi trigger No 772058337: Global MASTER-Net observations report
  97. GRB 250619A: Fermi GBM Final Real-time Localization
  98. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  99. Fermi GRB 250617A: Global MASTER-Net observations report
  100. GRB 250615A/EP250615a: FTW optical and NIR observations

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