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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"

32770 results found.

  1. EP250302a: Swift/UVOT detection
  2. EP250302a: NUTTelA-TAO Early Measurments
  3. EP250302a: optical observation from the INAF Asiago Observatory
  4. EP250302a: REM NIR upper limits
  5. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  6. EP250302a: Mondy Observations and Optical Light Curve
  7. EP250302a: VLT/MUSE optical redshift z = 1.131
  8. INTEGRAL: end of scientific operations
  9. EP250302A: VLT near-infrared observations
  10. EP250302A: VLT/X-shooter tentative redshift
  11. EP250302a: OHP/T193 optical and spectroscopic observations
  12. EP250302a: Global MASTER-Net observations report
  13. EP250302a: Xinglong F60B optical observation
  14. EP250302a: Swift-XRT observations of a fading X-ray source
  15. EP250302a: Einstein Probe detection of an X-ray transient
  16. EP250302a: SVOM/C-GFT optical observations
  17. GRB 250226A: GRANDMA Optical Observations
  18. EP250302a: Montarrenti Observatory optical detection
  19. Fermi GRB 250302A: Global MASTER-Net observations report
  20. EP250302a: FTW optical and NIR detection
  21. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  22. GRB 250225B: VLT near-infrared afterglow confirmation
  23. EP250228a: Optical observations with Kinder and Swift/UVOT
  24. Konus-Wind detection of GRB 250226A
  25. GRB 250225B: EIRSAT-1 GMOD Detection
  26. GRB 250226A: KAO Optical Upper Limit
  27. GRB 250226A: AbAO AS-32 Optical Upper Limit
  28. EP250227a: Global MASTER-Net observations report
  29. EP250223A: Upper limits from Fermi-GBM Observations
  30. EP250227a: TRT optical upper limit
  31. GRB 250225B: VLT/HAWKI near-infrared observations
  32. EP250227a: Optical upper limits with Kinder observations
  33. EP250227a: NOT optical observations
  34. EP250228a: updates on the EP observations
  35. GRB 250226A: Fermi GBM Observation
  36. EP250225a: EP-FXT follow-up observation
  37. EP250223a: J band upper limit by SYSU 80cm telescope
  38. EP250228a: Swift/XRT localisation
  39. EP250228a: Global MASTER-Net observations report
  40. GRB 250226A / EP250226a: LCO detection of the afterglow
  41. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  42. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  43. GRB 250225B: VLT/Xshooter imaging
  44. GRB 250205A / EP250205A: further radio observations with the VLA
  45. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  46. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  47. GRB 250225B: INTEGRAL SPI-ACS detection
  48. EP250225a: NOT optical candidate counterpart
  49. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  50. EP250226a / GRB 250226A: SVOM/VT optical observations
  51. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  52. EP250225a: TRT optical upper limits
  53. EP250226a/GRB 250226A: 1.6m Mephisto observations
  54. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  55. EP250226a/GRB 250226A: Kinder optical follow-up observations
  56. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  57. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  58. Fermi GRB 250226B: Global MASTER-Net observations report
  59. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  60. GRB 250225B: Fermi GBM Observation
  61. GRB 250221A: ATCA Detections and Upper Limits
  62. GRB 250225B: REM NIR upper limits
  63. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  64. Konus-Wind detection of GRB 250225B
  65. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  66. EP250223a: CrAO ZTSH optical observation
  67. GRB 250225B: VLT optical and near-infrared candidate counterpart
  68. GRB 250225B: VLT/FORS2 candidate optical afterglow
  69. GRB 250225B: SVOM/GRM observation of a long burst
  70. GRB 250226A: GECAM-B detection
  71. GRB 250221A: EP-FXT detection of the X-ray afterglow
  72. GRB 250214A: SVOM/GRM observation
  73. EP250226a/GRB 250226A: GSP detects optical counterpart
  74. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  75. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  76. EP250226a / GRB 250226A: TRT optical counterpart observation
  77. EP250226a: Global MASTER-Net observations report
  78. Swift GRB 250225B: Global MASTER-Net observations report
  79. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  80. Fermi GRB 250226A: Global MASTER-Net observations report
  81. EP250225a: Global MASTER-Net observations report
  82. EP250225a: GSP optical upper limit
  83. EP250223a: GMG Optical Observation
  84. Fermi GRB 250225A: Global MASTER-Net observations report
  85. EP250223a: GROWTH-India Telescope optical observations
  86. GRB 250221A: Swift-BAT refined analysis
  87. GRB 250223C: SVOM/GRM observation of a long burst
  88. EP250215A: J band upper limit by SYSU 80cm telescope
  89. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  90. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  91. EP250223a: Kinder optical follow-up observations
  92. GRB 250207a: ATCA Radio Upper Limits
  93. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  94. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  95. GRB 250119B: VZLUSAT-2 detection
  96. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  97. GRB 250202B: VZLUSAT-2 detection
  98. GRB 250219A: EP-FXT afterglow detection
  99. EP250223a: GOTO optical afterglow detections
  100. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading

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