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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"

24368 results found.

  1. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  2. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  3. Fermi GRB 250703A: Global MASTER-Net observations report
  4. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  5. GRB 250702F: Swift-XRT refined Analysis
  6. GRB 250702F: Fermi GBM Observation
  7. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  8. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  9. GRB 250702A: GECAM-B detection
  10. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  11. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  12. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  13. GRB 250702F: REM optical afterglow detection
  14. EP250702a: Global MASTER-Net observations report
  15. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  16. GRB 250703A: Fermi GBM Final Real-time Localization
  17. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  18. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  19. Fermi GRB 250702E: Global MASTER-Net observations report
  20. Fermi GRB 250702B: Global MASTER-Net observations report
  21. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  22. Fermi GRB 250702F: Global MASTER-Net observations report
  23. Fermi GRB 250702C: Global MASTER-Net observations report
  24. Swift GRB 250702F: Global MASTER-Net observations report
  25. GRB 250702F: Fermi GBM Final Real-time Localization
  26. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  27. GRB 250702E: Fermi GBM Final Real-time Localization
  28. Konus-Wind detection of GRB 250627A
  29. IPN triangulation of GRB 250627A (short)
  30. GRB 250702A: Fermi GBM Detection
  31. GRB 250702D: Fermi GBM Final Localization Correction
  32. GRB 250702C: Fermi GBM Final Real-time Localization
  33. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  34. GRB 250702B: Fermi GBM Final Real-time Localization
  35. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  36. GRB 250702A: Fermi GBM Final Real-time Localization
  37. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  39. GRB 250628B: SVOM/VT optical upper limit
  40. GRB 250628B: EP-FXT counterpart detection
  41. LIGO/Virgo/KAGRA S250629bs: Updated Sky localization
  42. GRB 250627A: SVOM/GRM detection of a short burst
  43. LIGO/Virgo/KAGRA S250629ae: Updated Sky localization
  44. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S250628am: Updated Sky localization
  47. GRB 250628A: REM optical/NIR upper limits
  48. GRB 250628C: Fermi GBM Final Real-time Localization
  49. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  50. GRB 250628B: SVOM detection of a long burst
  51. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  52. Fermi GRB 250626A: Global MASTER-Net observations report
  53. Swift GRB 250628A: Global MASTER-Net observations report
  54. GRB 250628A: Swift detection of a burst
  55. GRB 250625A: Swift-BAT refined analysis
  56. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  57. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  58. GRB 250626A: Fermi GBM Final Real-time Localization
  59. GRB 250625A: SVOM/C-GFT upper limit in early phase
  60. GRB 250625A: GECAM-B detection
  61. GRB 250625A: ABObservatory afterglow detection
  62. GRB 250625A: Fermi-LAT detection
  63. GRB250625A: Fermi GBM Observation
  64. Swift GRB 250625A: Global MASTER-Net observations report
  65. GRB 250625A: NOT z-band upper limit
  66. GRB 250625A: SVOM/VT optical confirmation
  67. GRB 250620B: Fermi GBM Observation
  68. Fermi GRB 250625A: Global MASTER-Net observations report
  69. GRB 250625A: Swift detection of a burst
  70. GRB 250625A: Fermi GBM Final Real-time Localization
  71. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  72. Fermi GRB 250624A: Global MASTER-Net observations report
  73. GRB 250624A: Fermi GBM Final Real-time Localization
  74. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  75. Fermi GRB 250623A: Global MASTER-Net observations report
  76. GRB 250623A: Fermi GBM Final Real-time Localization
  77. GRB 250521A: VZLUSAT-2 detection
  78. GRB 250617B: Swift-BAT refined analysis
  79. Fermi trigger No 772190032: Global MASTER-Net observations report
  80. Konus-Wind detection of GRB 250620C
  81. IPN triangulation of GRB 250620C (long/bright)
  82. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  83. GRB 250620C: SVOM/GRM observation
  84. GRB 250620A: SVOM/GRM observation of a short burst
  85. GRB250620A: Fermi GBM Observation
  86. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  87. Fermi GRB 250621A: Global MASTER-Net observations report
  88. GRB 250619B: Fermi GBM Observation
  89. GRB 250621A: Fermi GBM Final Real-time Localization
  90. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  91. GRB250620C: Fermi GBM Observation
  92. GRB 250506A - SVOM/ECLAIRs Refined analysis
  93. The EP-WXT trigger 01709179071 is likely a flaring star
  94. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  95. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  96. GRB 250620C: Fermi GBM Final Real-time Localization
  97. Fermi trigger No 772128434: Global MASTER-Net observations report
  98. GRB 250620B: Fermi GBM Final Real-time Localization
  99. GRB 250620A: Fermi GBM Final Real-time Localization
  100. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278

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