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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"

37565 results found.

  1. IPN triangulation of GRB 250222A
  2. EP250302a: Mondy Continued Optical Observations
  3. EP250304a: VLT/X-shooter redshift z = 0.200
  4. EP250302a: Mondy Observations and Optical Light Curve
  5. EP250302a: OHP/T193 optical and spectroscopic observations
  6. GRB 250226A: GRANDMA Optical Observations
  7. EP250302a: Montarrenti Observatory optical detection
  8. Fermi GRB 250302A: Global MASTER-Net observations report
  9. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 250302A: Fermi GBM Final Real-time Localization
  11. GRB 250228A: Fermi GBM Final Localization
  12. GRB 250225B: VLT near-infrared afterglow confirmation
  13. Konus-Wind detection of GRB 250226A
  14. GRB 250225B: EIRSAT-1 GMOD Detection
  15. GRB 250226A: KAO Optical Upper Limit
  16. GRB 250226A: AbAO AS-32 Optical Upper Limit
  17. EP250223A: Upper limits from Fermi-GBM Observations
  18. GRB 250225B: VLT/HAWKI near-infrared observations
  19. GRB 250226A: Fermi GBM Observation
  20. GRB 250226A / EP250226a: LCO detection of the afterglow
  21. GRB 250225B: VLT/Xshooter imaging
  22. GRB 250205A / EP250205A: further radio observations with the VLA
  23. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  24. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  25. GRB 250225B: INTEGRAL SPI-ACS detection
  26. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  27. EP250226a / GRB 250226A: SVOM/VT optical observations
  28. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  29. EP250226a/GRB 250226A: 1.6m Mephisto observations
  30. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  31. EP250226a/GRB 250226A: Kinder optical follow-up observations
  32. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  33. Fermi GRB 250226B: Global MASTER-Net observations report
  34. GRB 250226B: Fermi GBM Final Real-time Localization
  35. GRB 250225B: Fermi GBM Observation
  36. GRB 250221A: ATCA Detections and Upper Limits
  37. GRB 250225B: REM NIR upper limits
  38. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  39. Konus-Wind detection of GRB 250225B
  40. EP250223a: CrAO ZTSH optical observation
  41. GRB 250225B: VLT optical and near-infrared candidate counterpart
  42. GRB 250225B: VLT/FORS2 candidate optical afterglow
  43. GRB 250225B: SVOM/GRM observation of a long burst
  44. GRB 250226A: GECAM-B detection
  45. GRB 250221A: EP-FXT detection of the X-ray afterglow
  46. GRB 250214A: SVOM/GRM observation
  47. EP250226a/GRB 250226A: GSP detects optical counterpart
  48. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  49. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  50. EP250226a / GRB 250226A: TRT optical counterpart observation
  51. Swift GRB 250225B: Global MASTER-Net observations report
  52. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  53. Fermi GRB 250226A: Global MASTER-Net observations report
  54. Fermi trigger No 762205158: Global MASTER-Net observations report
  55. GRB 250226A: Fermi GBM Final Real-time Localization
  56. Fermi GRB 250225A: Global MASTER-Net observations report
  57. GRB 250225B: Swift detection of a burst
  58. GRB 250221A: Swift-BAT refined analysis
  59. GRB 250223C: SVOM/GRM observation of a long burst
  60. EP250215A: J band upper limit by SYSU 80cm telescope
  61. GRB 250225A: Fermi GBM Final Real-time Localization
  62. GRB 250207a: ATCA Radio Upper Limits
  63. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  64. GRB 250119B: VZLUSAT-2 detection
  65. GRB 250223C: Fermi GBM Final Real-time Localization
  66. GRB 250202B: VZLUSAT-2 detection
  67. GRB 250219A: EP-FXT afterglow detection
  68. GRB 250222A: SVOM/GRM observation of a burst
  69. GRB 250210A: VZLUSAT-2 detection
  70. GRB 250206A: VZLUSAT-2 detection
  71. GRB 250221A: TNOT detection of the optical counterpart
  72. 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
  73. EP250223a: OASDG optical observations
  74. GRB 250223B: Fermi GBM Final Localization
  75. GRB 250221A: VLA radio detection
  76. Fermi GRB 250223A: Global MASTER-Net observations report
  77. Fermi trigger No 762020305: Global MASTER-Net observations report
  78. GRB 250223A: Fermi GBM Final Real-time Localization
  79. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  80. GRB 250221A: continued Mondy optical observations, brightening afterglow
  81. GRB 250221A: Optical counterpart detection by LCO.
  82. GRB 250221A: Mondy optical observations
  83. Konus-Wind detection of GRB 250221A
  84. GRB 250221A: Assy optical observations
  85. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  86. GRB 250221A: VLT/X-shooter redshift z = 0.768
  87. GRB 250221A: GRANDMA/TAROT Detection
  88. Fermi trigger No 761805304: Global MASTER-Net observations report
  89. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  90. GRB 250221A: Swift-XRT refined Analysis
  91. GRB 250221A: NOT optical observations
  92. GRB 250221A: 1.6m Mephisto optical detection
  93. GRB 250221A: AKO Optical Upper Limit
  94. GRB 250221A: Swift/UVOT Detection
  95. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  96. GRB 250221A: REM optical/NIR afterglow detection
  97. GRB 250221A: Enhanced Swift-XRT position
  98. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  99. GRB 250221A: Swift detection of a burst with an optical counterpart
  100. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB

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