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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"

27216 results found.

  1. EP250302a: SVOM/C-GFT optical observations
  2. GRB 250226A: GRANDMA Optical Observations
  3. EP250302a: Montarrenti Observatory optical detection
  4. Fermi GRB 250302A: Global MASTER-Net observations report
  5. EP250302a: FTW optical and NIR detection
  6. EP250302a: Nanshan/HMT optical counterpart detection
  7. GRB 250302A: Fermi GBM Final Real-time Localization
  8. GRB 250228A: Fermi GBM Final Localization
  9. The EP-WXT trigger 01709132140 is likely a flaring star
  10. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  11. EP250228a: Optical observations with Kinder and Swift/UVOT
  12. GRB 250226A: KAO Optical Upper Limit
  13. GRB 250226A: AbAO AS-32 Optical Upper Limit
  14. EP250227a: Global MASTER-Net observations report
  15. EP250223A: Upper limits from Fermi-GBM Observations
  16. EP250227a: TRT optical upper limit
  17. GRB 250225B: VLT/HAWKI near-infrared observations
  18. EP250227a: Optical upper limits with Kinder observations
  19. EP250227a: NOT optical observations
  20. EP250227a: Einstein Probe detected of a fast X-ray transient
  21. EP250228a: updates on the EP observations
  22. GRB 250226A: Fermi GBM Observation
  23. EP250225a: EP-FXT follow-up observation
  24. EP250223a: J band upper limit by SYSU 80cm telescope
  25. EP250228a: Swift/XRT localisation
  26. EP250228a: Global MASTER-Net observations report
  27. EP250228a: Einstein Probe detection of an X-ray transient
  28. GRB 250226A / EP250226a: LCO detection of the afterglow
  29. EP250225a: NOT optical candidate counterpart
  30. EP250226a / GRB 250226A: SVOM/VT optical observations
  31. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  32. EP250226a/GRB 250226A: 1.6m Mephisto observations
  33. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  34. EP250226a/GRB 250226A: Kinder optical follow-up observations
  35. LIGO/Virgo/KAGRA S250227y: Retraction of GW compact binary merger candidate
  36. Fermi GRB 250226B: Global MASTER-Net observations report
  37. GRB 250226B: Fermi GBM Final Real-time Localization
  38. GRB 250225B: Fermi GBM Observation
  39. GRB 250225B: REM NIR upper limits
  40. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  41. GRB 250225B: SVOM/GRM observation of a long burst
  42. GRB 250226A: GECAM-B detection
  43. GRB 250221A: EP-FXT detection of the X-ray afterglow
  44. GRB 250214A: SVOM/GRM observation
  45. EP250226a/GRB 250226A: GSP detects optical counterpart
  46. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  47. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  48. EP250226a / GRB 250226A: TRT optical counterpart observation
  49. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  50. EP250226a: Global MASTER-Net observations report
  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. EP250225a: Global MASTER-Net observations report
  57. EP250225a: GSP optical upper limit
  58. EP250223a: GMG Optical Observation
  59. EP250225a: Einstein Probe detected of a fast X-ray transient
  60. Fermi GRB 250225A: Global MASTER-Net observations report
  61. GRB 250225B: Swift detection of a burst
  62. EP250223a: GROWTH-India Telescope optical observations
  63. GRB 250221A: Swift-BAT refined analysis
  64. GRB 250223C: SVOM/GRM observation of a long burst
  65. EP250215A: J band upper limit by SYSU 80cm telescope
  66. GRB 250225A: Fermi GBM Final Real-time Localization
  67. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  68. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  69. EP250223a: Kinder optical follow-up observations
  70. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  71. GRB 250223C: Fermi GBM Final Real-time Localization
  72. GRB 250202B: VZLUSAT-2 detection
  73. GRB 250219A: EP-FXT afterglow detection
  74. EP250223a: GOTO optical afterglow detections
  75. GRB 250222A: SVOM/GRM observation of a burst
  76. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  77. EP250223a: REM NIR upper limit
  78. EP250223a: TRT optical afterglow observation
  79. EP250223a: refined analysis of the EP-WXT and FXT observations
  80. EP250223a: 1.6m Mephisto and 50cm array observations
  81. EP250223a: SVOM/VT optical observation
  82. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  83. 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
  84. The EP-WXT trigger 01709131882 is likely a flaring star
  85. EP250223a: OASDG optical observations
  86. EP250223a: LCO detection of the afterglow
  87. EP250223a: early optical detection by BOOTES-4
  88. EP250223a: Swift/XRT localization
  89. EP250223a: NOT optical afterglow candidate
  90. GRB 250223B: Fermi GBM Final Localization
  91. EP250223a: Global MASTER-Net observations report
  92. GRB 250221A: VLA radio detection
  93. Fermi GRB 250223A: Global MASTER-Net observations report
  94. Fermi trigger No 762020305: Global MASTER-Net observations report
  95. GRB 250223A: Fermi GBM Final Real-time Localization
  96. EP250223a: Einstein Probe detection of an X-ray transient
  97. GRB 250221A: Optical counterpart detection by LCO.
  98. EP250220a: FTW optical and NIR observations and upper limits
  99. EP250220a: EP-FXT follow-up observations
  100. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits

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