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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"

18515 results found.

  1. EP250302a: SAO RAS optical observations
  2. EP250302a : GIT optical follow-up
  3. EP250302a: Kinder optical follow-up observations
  4. EP250302a: Swift/UVOT detection
  5. EP250302a: optical observation from the INAF Asiago Observatory
  6. EP250302a: REM NIR upper limits
  7. EP250302a: Mondy Observations and Optical Light Curve
  8. EP250302a: VLT/MUSE optical redshift z = 1.131
  9. EP250302A: VLT near-infrared observations
  10. EP250302A: VLT/X-shooter tentative redshift
  11. EP250302a: OHP/T193 optical and spectroscopic observations
  12. EP250302a: Einstein Probe detection of an X-ray transient
  13. EP250302a: SVOM/C-GFT optical observations
  14. GRB 250226A: GRANDMA Optical Observations
  15. EP250302a: Montarrenti Observatory optical detection
  16. EP250302a: Nanshan/HMT optical counterpart detection
  17. The EP-WXT trigger 01709132140 is likely a flaring star
  18. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  19. GRB 250225B: VLT near-infrared afterglow confirmation
  20. EP250228a: Optical observations with Kinder and Swift/UVOT
  21. GRB 250226A: KAO Optical Upper Limit
  22. GRB 250226A: AbAO AS-32 Optical Upper Limit
  23. EP250227a: TRT optical upper limit
  24. GRB 250225B: VLT/HAWKI near-infrared observations
  25. EP250227a: Optical upper limits with Kinder observations
  26. EP250227a: NOT optical observations
  27. EP250227a: Einstein Probe detected of a fast X-ray transient
  28. EP250228a: updates on the EP observations
  29. EP250225a: EP-FXT follow-up observation
  30. EP250223a: J band upper limit by SYSU 80cm telescope
  31. EP250228a: Einstein Probe detection of an X-ray transient
  32. GRB 250225B: VLT/Xshooter imaging
  33. GRB 250205A / EP250205A: further radio observations with the VLA
  34. EP250225a: NOT optical candidate counterpart
  35. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  36. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  37. EP250225a: TRT optical upper limits
  38. EP250226a/GRB 250226A: 1.6m Mephisto observations
  39. EP250226a/GRB 250226A: Kinder optical follow-up observations
  40. GRB 250221A: ATCA Detections and Upper Limits
  41. GRB 250225B: REM NIR upper limits
  42. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  43. EP250223a: CrAO ZTSH optical observation
  44. GRB 250225B: VLT optical and near-infrared candidate counterpart
  45. GRB 250225B: SVOM/GRM observation of a long burst
  46. GRB 250221A: EP-FXT detection of the X-ray afterglow
  47. EP250226a/GRB 250226A: GSP detects optical counterpart
  48. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  49. EP250226a / GRB 250226A: TRT optical counterpart observation
  50. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  51. EP250223a: GMG Optical Observation
  52. EP250225a: Einstein Probe detected of a fast X-ray transient
  53. EP250223a: GROWTH-India Telescope optical observations
  54. EP250215A: J band upper limit by SYSU 80cm telescope
  55. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  56. EP250223a: Kinder optical follow-up observations
  57. GRB 250207a: ATCA Radio Upper Limits
  58. GRB 250219A: EP-FXT afterglow detection
  59. GRB 250222A: SVOM/GRM observation of a burst
  60. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  61. EP250223a: REM NIR upper limit
  62. EP250223a: TRT optical afterglow observation
  63. EP250223a: refined analysis of the EP-WXT and FXT observations
  64. EP250223a: 1.6m Mephisto and 50cm array observations
  65. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  66. 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
  67. The EP-WXT trigger 01709131882 is likely a flaring star
  68. EP250223a: OASDG optical observations
  69. EP250223a: NOT optical afterglow candidate
  70. GRB 250221A: VLA radio detection
  71. EP250223a: Einstein Probe detection of an X-ray transient
  72. GRB 250221A: Optical counterpart detection by LCO.
  73. EP250220a: EP-FXT follow-up observations
  74. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  75. GRB 250221A: GRANDMA/TAROT Detection
  76. GRB 250221A: Swift-XRT refined Analysis
  77. GRB 250221A: 1.6m Mephisto optical detection
  78. GRB 250221A: AKO Optical Upper Limit
  79. GRB 250221A: Swift/UVOT Detection
  80. EP250220a: Liverpool Telescope upper limits
  81. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  82. GRB 250221A: REM optical/NIR afterglow detection
  83. GRB 250221A: Enhanced Swift-XRT position
  84. EP250220a: 1.6m Mephisto observations
  85. EP250220a: Liverpool Telescope optical upper limits
  86. EP250220a: Optical upper limit with Kinder observations
  87. SVOM trigger sb25022102 is not an astrophysical event
  88. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  89. GRB 250221A: Swift detection of a burst with an optical counterpart
  90. EP250220a: Xinglong optical upper limit
  91. EP250220a: EP-WXT detection of a fast X-ray transient
  92. GRB 250219A: Swift/UVOT Upper Limits
  93. GRB 250219A: OHP/T193 optical upper limit
  94. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  95. GRB 250219A: 1.6m Mephisto optical upper limits
  96. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  97. GRB 250217C: Swift-XRT observations
  98. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  99. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  100. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow

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