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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"

32688 results found.

  1. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  2. Konus-Wind detection of GRB 250222A
  3. EP250304a: REM NIR upper limits
  4. IPN triangulation of GRB 250222A
  5. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  6. EP250302a: Mondy Continued Optical Observations
  7. EP250304a: VLT/X-shooter redshift z = 0.200
  8. EP250304a: Swift-XRT detection of a fading X-ray source
  9. EP250304a: TRT optical counterpart detection
  10. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  11. EP250304a: Global MASTER-Net observations report
  12. EP250302a: SVOM/VT optical observation
  13. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  14. EP250302a: SAO RAS optical observations
  15. EP250302a : GIT optical follow-up
  16. EP250302a: VLT/X-shooter redshift confirmation
  17. EP250225a: the candidate optical counterpart is an AGN
  18. EP250302a: Kinder optical follow-up observations
  19. EP250302a: Swift/UVOT detection
  20. EP250302a: NUTTelA-TAO Early Measurments
  21. EP250302a: optical observation from the INAF Asiago Observatory
  22. EP250302a: REM NIR upper limits
  23. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  24. EP250302a: Mondy Observations and Optical Light Curve
  25. EP250302a: VLT/MUSE optical redshift z = 1.131
  26. INTEGRAL: end of scientific operations
  27. EP250302A: VLT near-infrared observations
  28. EP250302A: VLT/X-shooter tentative redshift
  29. EP250302a: OHP/T193 optical and spectroscopic observations
  30. EP250302a: Global MASTER-Net observations report
  31. EP250302a: Xinglong F60B optical observation
  32. EP250302a: Swift-XRT observations of a fading X-ray source
  33. EP250302a: Einstein Probe detection of an X-ray transient
  34. EP250302a: SVOM/C-GFT optical observations
  35. GRB 250226A: GRANDMA Optical Observations
  36. EP250302a: Montarrenti Observatory optical detection
  37. Fermi GRB 250302A: Global MASTER-Net observations report
  38. EP250302a: FTW optical and NIR detection
  39. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  40. GRB 250225B: VLT near-infrared afterglow confirmation
  41. EP250228a: Optical observations with Kinder and Swift/UVOT
  42. Konus-Wind detection of GRB 250226A
  43. GRB 250225B: EIRSAT-1 GMOD Detection
  44. GRB 250226A: KAO Optical Upper Limit
  45. GRB 250226A: AbAO AS-32 Optical Upper Limit
  46. EP250227a: Global MASTER-Net observations report
  47. EP250223A: Upper limits from Fermi-GBM Observations
  48. EP250227a: TRT optical upper limit
  49. GRB 250225B: VLT/HAWKI near-infrared observations
  50. EP250227a: Optical upper limits with Kinder observations
  51. EP250227a: NOT optical observations
  52. EP250228a: updates on the EP observations
  53. GRB 250226A: Fermi GBM Observation
  54. EP250225a: EP-FXT follow-up observation
  55. EP250223a: J band upper limit by SYSU 80cm telescope
  56. EP250228a: Swift/XRT localisation
  57. EP250228a: Global MASTER-Net observations report
  58. GRB 250226A / EP250226a: LCO detection of the afterglow
  59. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  60. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  61. GRB 250225B: VLT/Xshooter imaging
  62. GRB 250205A / EP250205A: further radio observations with the VLA
  63. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  64. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  65. GRB 250225B: INTEGRAL SPI-ACS detection
  66. EP250225a: NOT optical candidate counterpart
  67. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  68. EP250226a / GRB 250226A: SVOM/VT optical observations
  69. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  70. EP250225a: TRT optical upper limits
  71. EP250226a/GRB 250226A: 1.6m Mephisto observations
  72. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  73. EP250226a/GRB 250226A: Kinder optical follow-up observations
  74. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  75. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  76. Fermi GRB 250226B: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  78. GRB 250225B: Fermi GBM Observation
  79. GRB 250221A: ATCA Detections and Upper Limits
  80. GRB 250225B: REM NIR upper limits
  81. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  82. Konus-Wind detection of GRB 250225B
  83. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  84. EP250223a: CrAO ZTSH optical observation
  85. GRB 250225B: VLT optical and near-infrared candidate counterpart
  86. GRB 250225B: VLT/FORS2 candidate optical afterglow
  87. GRB 250225B: SVOM/GRM observation of a long burst
  88. GRB 250226A: GECAM-B detection
  89. GRB 250221A: EP-FXT detection of the X-ray afterglow
  90. GRB 250214A: SVOM/GRM observation
  91. EP250226a/GRB 250226A: GSP detects optical counterpart
  92. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  93. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  94. EP250226a / GRB 250226A: TRT optical counterpart observation
  95. EP250226a: Global MASTER-Net observations report
  96. Swift GRB 250225B: Global MASTER-Net observations report
  97. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  98. Fermi GRB 250226A: Global MASTER-Net observations report
  99. EP250225a: Global MASTER-Net observations report
  100. EP250225a: GSP optical upper limit

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