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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"

28294 results found.

  1. EP250302a: optical observation from the INAF Asiago Observatory
  2. EP250302a: REM NIR upper limits
  3. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  4. EP250302a: Mondy Observations and Optical Light Curve
  5. EP250302a: VLT/MUSE optical redshift z = 1.131
  6. EP250302A: VLT near-infrared observations
  7. EP250302A: VLT/X-shooter tentative redshift
  8. EP250302a: OHP/T193 optical and spectroscopic observations
  9. EP250302a: Swift-XRT observations of a fading X-ray source
  10. EP250302a: Einstein Probe detection of an X-ray transient
  11. EP250302a: SVOM/C-GFT optical observations
  12. GRB 250226A: GRANDMA Optical Observations
  13. EP250302a: Montarrenti Observatory optical detection
  14. EP250302a: Nanshan/HMT optical counterpart detection
  15. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  16. GRB 250225B: VLT near-infrared afterglow confirmation
  17. EP250228a: Optical observations with Kinder and Swift/UVOT
  18. Konus-Wind detection of GRB 250226A
  19. GRB 250225B: EIRSAT-1 GMOD Detection
  20. GRB 250226A: KAO Optical Upper Limit
  21. GRB 250226A: AbAO AS-32 Optical Upper Limit
  22. EP250227a: Global MASTER-Net observations report
  23. EP250223A: Upper limits from Fermi-GBM Observations
  24. EP250227a: TRT optical upper limit
  25. GRB 250225B: VLT/HAWKI near-infrared observations
  26. EP250227a: Optical upper limits with Kinder observations
  27. EP250227a: NOT optical observations
  28. EP250227a: Einstein Probe detected of a fast X-ray transient
  29. EP250228a: updates on the EP observations
  30. GRB 250226A: Fermi GBM Observation
  31. EP250223a: J band upper limit by SYSU 80cm telescope
  32. EP250228a: Swift/XRT localisation
  33. EP250228a: Einstein Probe detection of an X-ray transient
  34. GRB 250226A / EP250226a: LCO detection of the afterglow
  35. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  36. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  37. GRB 250225B: VLT/Xshooter imaging
  38. GRB 250205A / EP250205A: further radio observations with the VLA
  39. EP250225a: NOT optical candidate counterpart
  40. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  41. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  42. EP250225a: TRT optical upper limits
  43. EP250226a/GRB 250226A: 1.6m Mephisto observations
  44. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  45. EP250226a/GRB 250226A: Kinder optical follow-up observations
  46. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  47. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  49. GRB 250225B: Fermi GBM Observation
  50. GRB 250225B: REM NIR upper limits
  51. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  52. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  53. EP250223a: CrAO ZTSH optical observation
  54. GRB 250225B: VLT optical and near-infrared candidate counterpart
  55. GRB 250225B: SVOM/GRM observation of a long burst
  56. EP250226a/GRB 250226A: GSP detects optical counterpart
  57. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  58. EP250226a / GRB 250226A: TRT optical counterpart observation
  59. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  60. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  61. EP250225a: GSP optical upper limit
  62. EP250223a: GMG Optical Observation
  63. EP250225a: Einstein Probe detected of a fast X-ray transient
  64. GRB 250225B: Swift detection of a burst
  65. EP250223a: GROWTH-India Telescope optical observations
  66. GRB 250221A: Swift-BAT refined analysis
  67. EP250215A: J band upper limit by SYSU 80cm telescope
  68. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  69. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  70. EP250223a: Kinder optical follow-up observations
  71. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  72. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  73. GRB 250119B: VZLUSAT-2 detection
  74. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  75. GRB 250202B: VZLUSAT-2 detection
  76. GRB 250222A: SVOM/GRM observation of a burst
  77. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  78. GRB 250206A: VZLUSAT-2 detection
  79. EP250223a: REM NIR upper limit
  80. EP250223a: TRT optical afterglow observation
  81. EP250223a: refined analysis of the EP-WXT and FXT observations
  82. EP250223a: 1.6m Mephisto and 50cm array observations
  83. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  84. 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
  85. EP250223a: OASDG optical observations
  86. EP250223a: LCO detection of the afterglow
  87. EP250223a: Swift/XRT localization
  88. EP250223a: NOT optical afterglow candidate
  89. EP250223a: Einstein Probe detection of an X-ray transient
  90. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  91. GRB 250221A: Optical counterpart detection by LCO.
  92. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  93. GRB 250221A: GRANDMA/TAROT Detection
  94. GRB 250221A: Swift-XRT refined Analysis
  95. GRB 250221A: NOT optical observations
  96. GRB 250221A: 1.6m Mephisto optical detection
  97. GRB 250221A: AKO Optical Upper Limit
  98. GRB 250221A: Swift/UVOT Detection
  99. EP250220a: Liverpool Telescope upper limits
  100. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits

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