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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"

36260 results found.

  1. GRB 250306A: AstroSat CZTI detection
  2. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  3. Swift GRB 250306A: Global MASTER-Net observations report
  4. GRB 250306A: Swift detection of a burst
  5. GRB 250305A: SVOM/GRM observation of a burst
  6. EP250304A: Upper limits from Fermi-GBM Observations
  7. Fermi GRB 250305A: Global MASTER-Net observations report
  8. GRB 250305A: Fermi GBM Final Real-time Localization
  9. EP250302a: Optical Observations at CrAO and SAO RAS
  10. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  11. EP 250304A: Optical counterpart detection by LCO
  12. Konus-Wind detection of GRB 250222A
  13. IPN triangulation of GRB 250222A
  14. EP250302a: Mondy Continued Optical Observations
  15. EP250304a: VLT/X-shooter redshift z = 0.200
  16. EP250302a: Mondy Observations and Optical Light Curve
  17. EP250302a: OHP/T193 optical and spectroscopic observations
  18. GRB 250226A: GRANDMA Optical Observations
  19. EP250302a: Montarrenti Observatory optical detection
  20. Fermi GRB 250302A: Global MASTER-Net observations report
  21. GRB 250302A: Fermi GBM Final Real-time Localization
  22. GRB 250228A: Fermi GBM Final Localization
  23. GRB 250225B: VLT near-infrared afterglow confirmation
  24. Konus-Wind detection of GRB 250226A
  25. GRB 250225B: EIRSAT-1 GMOD Detection
  26. GRB 250226A: KAO Optical Upper Limit
  27. GRB 250226A: AbAO AS-32 Optical Upper Limit
  28. EP250223A: Upper limits from Fermi-GBM Observations
  29. GRB 250225B: VLT/HAWKI near-infrared observations
  30. GRB 250226A: Fermi GBM Observation
  31. GRB 250226A / EP250226a: LCO detection of the afterglow
  32. GRB 250225B: VLT/Xshooter imaging
  33. GRB 250205A / EP250205A: further radio observations with the VLA
  34. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  35. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  36. GRB 250225B: INTEGRAL SPI-ACS detection
  37. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  38. EP250226a / GRB 250226A: SVOM/VT optical observations
  39. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  40. EP250226a/GRB 250226A: 1.6m Mephisto observations
  41. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  42. EP250226a/GRB 250226A: Kinder optical follow-up observations
  43. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  44. Fermi GRB 250226B: Global MASTER-Net observations report
  45. GRB 250226B: Fermi GBM Final Real-time Localization
  46. GRB 250225B: Fermi GBM Observation
  47. GRB 250221A: ATCA Detections and Upper Limits
  48. GRB 250225B: REM NIR upper limits
  49. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  50. Konus-Wind detection of GRB 250225B
  51. EP250223a: CrAO ZTSH optical observation
  52. GRB 250225B: VLT optical and near-infrared candidate counterpart
  53. GRB 250225B: VLT/FORS2 candidate optical afterglow
  54. GRB 250225B: SVOM/GRM observation of a long burst
  55. GRB 250226A: GECAM-B detection
  56. GRB 250221A: EP-FXT detection of the X-ray afterglow
  57. GRB 250214A: SVOM/GRM observation
  58. EP250226a/GRB 250226A: GSP detects optical counterpart
  59. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  60. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  61. EP250226a / GRB 250226A: TRT optical counterpart observation
  62. Swift GRB 250225B: Global MASTER-Net observations report
  63. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  64. Fermi GRB 250226A: 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. GRB 250225A: Fermi GBM Final Real-time Localization
  71. GRB 250207a: ATCA Radio Upper Limits
  72. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  73. GRB 250119B: VZLUSAT-2 detection
  74. GRB 250223C: Fermi GBM Final Real-time Localization
  75. GRB 250202B: VZLUSAT-2 detection
  76. GRB 250219A: EP-FXT afterglow detection
  77. GRB 250222A: SVOM/GRM observation of a burst
  78. GRB 250210A: VZLUSAT-2 detection
  79. GRB 250206A: VZLUSAT-2 detection
  80. GRB 250221A: TNOT detection of the optical counterpart
  81. 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
  82. EP250223a: OASDG optical observations
  83. GRB 250223B: Fermi GBM Final Localization
  84. GRB 250221A: VLA radio detection
  85. Fermi GRB 250223A: Global MASTER-Net observations report
  86. GRB 250223A: Fermi GBM Final Real-time Localization
  87. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  88. GRB 250221A: continued Mondy optical observations, brightening afterglow
  89. GRB 250221A: Optical counterpart detection by LCO.
  90. GRB 250221A: Mondy optical observations
  91. Konus-Wind detection of GRB 250221A
  92. GRB 250221A: Assy optical observations
  93. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  94. GRB 250221A: VLT/X-shooter redshift z = 0.768
  95. GRB 250221A: GRANDMA/TAROT Detection
  96. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  97. GRB 250221A: Swift-XRT refined Analysis
  98. GRB 250221A: NOT optical observations
  99. GRB 250221A: 1.6m Mephisto optical detection
  100. GRB 250221A: AKO Optical Upper Limit

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