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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"

37283 results found.

  1. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  2. IceCube-250309A: No candidates from the Zwicky Transient Facility
  3. Fermi-LAT gamma-ray observations of IceCube-250309A
  4. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  5. GRB 250309B: Fermi GBM Final Localization
  6. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  7. GRB 230509B: Tiled Swift observations
  8. GRB 250308A: SVOM/GRM observation of a bright short burst
  9. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  11. GRB 250309A: Fermi GBM Final Real-time Localization
  12. GRB 250306A: EIRSAT-1 GMOD detection
  13. Fermi GRB 250307A: Global MASTER-Net observations report
  14. Konus-Wind detection of GRB 250306A
  15. GRB 250307A: Fermi GBM Final Real-time Localization
  16. GRB 250306A: Swift-BAT refined analysis
  17. GRB 250306A: NuSTAR detection of the prompt emission
  18. GRB 250305A: AstroSat CZTI detection
  19. GRB 250306A: AstroSat CZTI detection
  20. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  21. Swift GRB 250306A: Global MASTER-Net observations report
  22. GRB 250306A: Swift detection of a burst
  23. GRB 250305A: SVOM/GRM observation of a burst
  24. EP250304A: Upper limits from Fermi-GBM Observations
  25. Fermi GRB 250305A: Global MASTER-Net observations report
  26. GRB 250305A: Fermi GBM Final Real-time Localization
  27. EP250302a: Optical Observations at CrAO and SAO RAS
  28. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  29. EP 250304A: Optical counterpart detection by LCO
  30. Konus-Wind detection of GRB 250222A
  31. IPN triangulation of GRB 250222A
  32. EP250302a: Mondy Continued Optical Observations
  33. EP250304a: VLT/X-shooter redshift z = 0.200
  34. EP250304a: Swift-XRT detection of a fading X-ray source
  35. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  36. EP250302a: Kinder optical follow-up observations
  37. EP250302a: Mondy Observations and Optical Light Curve
  38. EP250302a: OHP/T193 optical and spectroscopic observations
  39. GRB 250226A: GRANDMA Optical Observations
  40. EP250302a: Montarrenti Observatory optical detection
  41. Fermi GRB 250302A: Global MASTER-Net observations report
  42. GRB 250302A: Fermi GBM Final Real-time Localization
  43. GRB 250228A: Fermi GBM Final Localization
  44. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  45. GRB 250225B: VLT near-infrared afterglow confirmation
  46. EP250228a: Optical observations with Kinder and Swift/UVOT
  47. Konus-Wind detection of GRB 250226A
  48. GRB 250225B: EIRSAT-1 GMOD Detection
  49. GRB 250226A: KAO Optical Upper Limit
  50. GRB 250226A: AbAO AS-32 Optical Upper Limit
  51. EP250223A: Upper limits from Fermi-GBM Observations
  52. GRB 250225B: VLT/HAWKI near-infrared observations
  53. EP250227a: Optical upper limits with Kinder observations
  54. GRB 250226A: Fermi GBM Observation
  55. EP250223a: J band upper limit by SYSU 80cm telescope
  56. GRB 250226A / EP250226a: LCO detection of the afterglow
  57. GRB 250225B: VLT/Xshooter imaging
  58. GRB 250205A / EP250205A: further radio observations with the VLA
  59. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  60. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  61. GRB 250225B: INTEGRAL SPI-ACS detection
  62. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  63. EP250226a / GRB 250226A: SVOM/VT optical observations
  64. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  65. EP250226a/GRB 250226A: 1.6m Mephisto observations
  66. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  67. EP250226a/GRB 250226A: Kinder optical follow-up observations
  68. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  69. Fermi GRB 250226B: Global MASTER-Net observations report
  70. GRB 250226B: Fermi GBM Final Real-time Localization
  71. GRB 250225B: Fermi GBM Observation
  72. GRB 250221A: ATCA Detections and Upper Limits
  73. GRB 250225B: REM NIR upper limits
  74. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  75. Konus-Wind detection of GRB 250225B
  76. EP250223a: CrAO ZTSH optical observation
  77. GRB 250225B: VLT optical and near-infrared candidate counterpart
  78. GRB 250225B: VLT/FORS2 candidate optical afterglow
  79. GRB 250225B: SVOM/GRM observation of a long burst
  80. GRB 250226A: GECAM-B detection
  81. GRB 250221A: EP-FXT detection of the X-ray afterglow
  82. GRB 250214A: SVOM/GRM observation
  83. EP250226a/GRB 250226A: GSP detects optical counterpart
  84. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  85. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  86. EP250226a / GRB 250226A: TRT optical counterpart observation
  87. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  88. Swift GRB 250225B: Global MASTER-Net observations report
  89. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  90. Fermi GRB 250226A: Global MASTER-Net observations report
  91. GRB 250226A: Fermi GBM Final Real-time Localization
  92. Fermi GRB 250225A: Global MASTER-Net observations report
  93. GRB 250225B: Swift detection of a burst
  94. GRB 250221A: Swift-BAT refined analysis
  95. GRB 250223C: SVOM/GRM observation of a long burst
  96. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  97. GRB 250225A: Fermi GBM Final Real-time Localization
  98. EP250223a: Kinder optical follow-up observations
  99. GRB 250207a: ATCA Radio Upper Limits
  100. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations

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