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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"

27221 results found.

  1. EP250302a: OHP/T193 optical and spectroscopic observations
  2. EP250302a: Global MASTER-Net observations report
  3. EP250302a: Xinglong F60B optical observation
  4. EP250302a: Swift-XRT observations of a fading X-ray source
  5. EP250302a: Einstein Probe detection of an X-ray transient
  6. EP250302a: SVOM/C-GFT optical observations
  7. GRB 250226A: GRANDMA Optical Observations
  8. EP250302a: Montarrenti Observatory optical detection
  9. Fermi GRB 250302A: Global MASTER-Net observations report
  10. EP250302a: FTW optical and NIR detection
  11. EP250302a: Nanshan/HMT optical counterpart detection
  12. GRB 250302A: Fermi GBM Final Real-time Localization
  13. GRB 250228A: Fermi GBM Final Localization
  14. The EP-WXT trigger 01709132140 is likely a flaring star
  15. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  16. EP250228a: Optical observations with Kinder and Swift/UVOT
  17. GRB 250226A: KAO Optical Upper Limit
  18. GRB 250226A: AbAO AS-32 Optical Upper Limit
  19. EP250227a: Global MASTER-Net observations report
  20. EP250223A: Upper limits from Fermi-GBM Observations
  21. EP250227a: TRT optical upper limit
  22. GRB 250225B: VLT/HAWKI near-infrared observations
  23. EP250227a: Optical upper limits with Kinder observations
  24. EP250227a: NOT optical observations
  25. EP250227a: Einstein Probe detected of a fast X-ray transient
  26. EP250228a: updates on the EP observations
  27. GRB 250226A: Fermi GBM Observation
  28. EP250225a: EP-FXT follow-up observation
  29. EP250223a: J band upper limit by SYSU 80cm telescope
  30. EP250228a: Swift/XRT localisation
  31. EP250228a: Global MASTER-Net observations report
  32. EP250228a: Einstein Probe detection of an X-ray transient
  33. GRB 250226A / EP250226a: LCO detection of the afterglow
  34. EP250225a: NOT optical candidate counterpart
  35. EP250226a / GRB 250226A: SVOM/VT optical observations
  36. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  37. EP250226a/GRB 250226A: 1.6m Mephisto observations
  38. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  39. EP250226a/GRB 250226A: Kinder optical follow-up observations
  40. LIGO/Virgo/KAGRA S250227y: Retraction of GW compact binary merger candidate
  41. Fermi GRB 250226B: Global MASTER-Net observations report
  42. GRB 250226B: Fermi GBM Final Real-time Localization
  43. GRB 250225B: Fermi GBM Observation
  44. GRB 250225B: REM NIR upper limits
  45. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  46. GRB 250225B: SVOM/GRM observation of a long burst
  47. GRB 250226A: GECAM-B detection
  48. GRB 250221A: EP-FXT detection of the X-ray afterglow
  49. GRB 250214A: SVOM/GRM observation
  50. EP250226a/GRB 250226A: GSP detects optical counterpart
  51. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  52. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  53. EP250226a / GRB 250226A: TRT optical counterpart observation
  54. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  55. EP250226a: Global MASTER-Net observations report
  56. Swift GRB 250225B: Global MASTER-Net observations report
  57. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  58. Fermi GRB 250226A: Global MASTER-Net observations report
  59. Fermi trigger No 762205158: Global MASTER-Net observations report
  60. GRB 250226A: Fermi GBM Final Real-time Localization
  61. EP250225a: Global MASTER-Net observations report
  62. EP250225a: GSP optical upper limit
  63. EP250223a: GMG Optical Observation
  64. EP250225a: Einstein Probe detected of a fast X-ray transient
  65. Fermi GRB 250225A: Global MASTER-Net observations report
  66. GRB 250225B: Swift detection of a burst
  67. EP250223a: GROWTH-India Telescope optical observations
  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. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  73. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  74. EP250223a: Kinder optical follow-up observations
  75. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  76. GRB 250223C: Fermi GBM Final Real-time Localization
  77. GRB 250202B: VZLUSAT-2 detection
  78. GRB 250219A: EP-FXT afterglow detection
  79. EP250223a: GOTO optical afterglow detections
  80. GRB 250222A: SVOM/GRM observation of a burst
  81. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  82. EP250223a: REM NIR upper limit
  83. EP250223a: TRT optical afterglow observation
  84. EP250223a: refined analysis of the EP-WXT and FXT observations
  85. EP250223a: 1.6m Mephisto and 50cm array observations
  86. EP250223a: SVOM/VT optical observation
  87. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  88. 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
  89. The EP-WXT trigger 01709131882 is likely a flaring star
  90. EP250223a: OASDG optical observations
  91. EP250223a: LCO detection of the afterglow
  92. EP250223a: early optical detection by BOOTES-4
  93. EP250223a: Swift/XRT localization
  94. EP250223a: NOT optical afterglow candidate
  95. GRB 250223B: Fermi GBM Final Localization
  96. EP250223a: Global MASTER-Net observations report
  97. GRB 250221A: VLA radio detection
  98. Fermi GRB 250223A: Global MASTER-Net observations report
  99. Fermi trigger No 762020305: Global MASTER-Net observations report
  100. GRB 250223A: Fermi GBM Final Real-time Localization

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