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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

37675 results found.

  1. GRB 250306A: Swift detection of a burst
  2. GRB 250305A: SVOM/GRM observation of a burst
  3. EP250304A: Upper limits from Fermi-GBM Observations
  4. Fermi GRB 250305A: Global MASTER-Net observations report
  5. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  6. GRB 250305A: Fermi GBM Final Real-time Localization
  7. EP250302a: Optical Observations at CrAO and SAO RAS
  8. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  9. EP 250304A: Optical counterpart detection by LCO
  10. Konus-Wind detection of GRB 250222A
  11. IPN triangulation of GRB 250222A
  12. EP250302a: Mondy Continued Optical Observations
  13. EP250304a: VLT/X-shooter redshift z = 0.200
  14. EP250302a: Mondy Observations and Optical Light Curve
  15. EP250302a: OHP/T193 optical and spectroscopic observations
  16. GRB 250226A: GRANDMA Optical Observations
  17. EP250302a: Montarrenti Observatory optical detection
  18. Fermi GRB 250302A: Global MASTER-Net observations report
  19. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  20. GRB 250302A: Fermi GBM Final Real-time Localization
  21. GRB 250228A: Fermi GBM Final Localization
  22. GRB 250225B: VLT near-infrared afterglow confirmation
  23. Konus-Wind detection of GRB 250226A
  24. GRB 250225B: EIRSAT-1 GMOD Detection
  25. GRB 250226A: KAO Optical Upper Limit
  26. GRB 250226A: AbAO AS-32 Optical Upper Limit
  27. EP250223A: Upper limits from Fermi-GBM Observations
  28. GRB 250225B: VLT/HAWKI near-infrared observations
  29. GRB 250226A: Fermi GBM Observation
  30. GRB 250226A / EP250226a: LCO detection of the afterglow
  31. GRB 250225B: VLT/Xshooter imaging
  32. GRB 250205A / EP250205A: further radio observations with the VLA
  33. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  34. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  35. GRB 250225B: INTEGRAL SPI-ACS detection
  36. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  37. EP250226a / GRB 250226A: SVOM/VT optical observations
  38. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  39. EP250226a/GRB 250226A: 1.6m Mephisto observations
  40. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  41. EP250226a/GRB 250226A: Kinder optical follow-up observations
  42. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  43. Fermi GRB 250226B: Global MASTER-Net observations report
  44. GRB 250226B: Fermi GBM Final Real-time Localization
  45. GRB 250225B: Fermi GBM Observation
  46. GRB 250221A: ATCA Detections and Upper Limits
  47. GRB 250225B: REM NIR upper limits
  48. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  49. Konus-Wind detection of GRB 250225B
  50. EP250223a: CrAO ZTSH optical observation
  51. GRB 250225B: VLT optical and near-infrared candidate counterpart
  52. GRB 250225B: VLT/FORS2 candidate optical afterglow
  53. GRB 250225B: SVOM/GRM observation of a long burst
  54. GRB 250226A: GECAM-B detection
  55. GRB 250221A: EP-FXT detection of the X-ray afterglow
  56. GRB 250214A: SVOM/GRM observation
  57. EP250226a/GRB 250226A: GSP detects optical counterpart
  58. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  59. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  60. EP250226a / GRB 250226A: TRT optical counterpart observation
  61. Swift GRB 250225B: Global MASTER-Net observations report
  62. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  63. Fermi GRB 250226A: Global MASTER-Net observations report
  64. Fermi trigger No 762205158: Global MASTER-Net observations report
  65. GRB 250226A: Fermi GBM Final Real-time Localization
  66. Fermi GRB 250225A: Global MASTER-Net observations report
  67. GRB 250225B: Swift detection of a burst
  68. GRB 250221A: Swift-BAT refined analysis
  69. GRB 250223C: SVOM/GRM observation of a long burst
  70. EP250215A: J band upper limit by SYSU 80cm telescope
  71. GRB 250225A: Fermi GBM Final Real-time Localization
  72. GRB 250207a: ATCA Radio Upper Limits
  73. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  74. GRB 250119B: VZLUSAT-2 detection
  75. GRB 250223C: Fermi GBM Final Real-time Localization
  76. GRB 250202B: VZLUSAT-2 detection
  77. GRB 250219A: EP-FXT afterglow detection
  78. GRB 250222A: SVOM/GRM observation of a burst
  79. GRB 250210A: VZLUSAT-2 detection
  80. GRB 250206A: VZLUSAT-2 detection
  81. GRB 250221A: TNOT detection of the optical counterpart
  82. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  83. EP250223a: OASDG optical observations
  84. GRB 250223B: Fermi GBM Final Localization
  85. GRB 250221A: VLA radio detection
  86. Fermi GRB 250223A: Global MASTER-Net observations report
  87. Fermi trigger No 762020305: Global MASTER-Net observations report
  88. GRB 250223A: Fermi GBM Final Real-time Localization
  89. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  90. GRB 250221A: continued Mondy optical observations, brightening afterglow
  91. GRB 250221A: Optical counterpart detection by LCO.
  92. GRB 250221A: Mondy optical observations
  93. Konus-Wind detection of GRB 250221A
  94. GRB 250221A: Assy optical observations
  95. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  96. GRB 250221A: VLT/X-shooter redshift z = 0.768
  97. GRB 250221A: GRANDMA/TAROT Detection
  98. Fermi trigger No 761805304: Global MASTER-Net observations report
  99. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  100. GRB 250221A: Swift-XRT refined Analysis

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