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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"

28116 results found.

  1. The EP-WXT trigger 01709132323 is likely a flaring star
  2. EP250304A: Upper limits from Fermi-GBM Observations
  3. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  4. EP250302a: Optical Observations at CrAO and SAO RAS
  5. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  6. EP 250304A: Optical counterpart detection by LCO
  7. EP250302A: 1.3m DFOT optical afterglow detection
  8. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  9. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  10. EP250304a: REM NIR upper limits
  11. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  12. EP250302a: Mondy Continued Optical Observations
  13. EP250304a: Swift-XRT detection of a fading X-ray source
  14. EP250304a: TRT optical counterpart detection
  15. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  16. EP250304a: Einstein Probe detection of an X-ray transient
  17. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  18. EP250302a: SAO RAS optical observations
  19. EP250302a : GIT optical follow-up
  20. EP250225a: the candidate optical counterpart is an AGN
  21. EP250302a: Kinder optical follow-up observations
  22. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  23. EP250302a: Swift/UVOT detection
  24. EP250302a: optical observation from the INAF Asiago Observatory
  25. EP250302a: REM NIR upper limits
  26. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  27. EP250302a: Mondy Observations and Optical Light Curve
  28. EP250302a: VLT/MUSE optical redshift z = 1.131
  29. EP250302A: VLT near-infrared observations
  30. EP250302A: VLT/X-shooter tentative redshift
  31. EP250302a: OHP/T193 optical and spectroscopic observations
  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. EP250302a: Nanshan/HMT optical counterpart detection
  38. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  39. GRB 250225B: VLT near-infrared afterglow confirmation
  40. EP250228a: Optical observations with Kinder and Swift/UVOT
  41. Konus-Wind detection of GRB 250226A
  42. GRB 250225B: EIRSAT-1 GMOD Detection
  43. GRB 250226A: KAO Optical Upper Limit
  44. GRB 250226A: AbAO AS-32 Optical Upper Limit
  45. EP250227a: Global MASTER-Net observations report
  46. EP250223A: Upper limits from Fermi-GBM Observations
  47. EP250227a: TRT optical upper limit
  48. GRB 250225B: VLT/HAWKI near-infrared observations
  49. EP250227a: Optical upper limits with Kinder observations
  50. EP250227a: NOT optical observations
  51. EP250227a: Einstein Probe detected of a fast X-ray transient
  52. EP250228a: updates on the EP observations
  53. GRB 250226A: Fermi GBM Observation
  54. EP250223a: J band upper limit by SYSU 80cm telescope
  55. EP250228a: Swift/XRT localisation
  56. EP250228a: Einstein Probe detection of an X-ray transient
  57. GRB 250226A / EP250226a: LCO detection of the afterglow
  58. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  59. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  60. GRB 250225B: VLT/Xshooter imaging
  61. GRB 250205A / EP250205A: further radio observations with the VLA
  62. EP250225a: NOT optical candidate counterpart
  63. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  64. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  65. EP250225a: TRT optical upper limits
  66. EP250226a/GRB 250226A: 1.6m Mephisto observations
  67. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  68. EP250226a/GRB 250226A: Kinder optical follow-up observations
  69. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  70. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  72. GRB 250225B: Fermi GBM Observation
  73. GRB 250225B: REM NIR upper limits
  74. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  75. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  76. EP250223a: CrAO ZTSH optical observation
  77. GRB 250225B: VLT optical and near-infrared candidate counterpart
  78. GRB 250225B: SVOM/GRM observation of a long burst
  79. EP250226a/GRB 250226A: GSP detects optical counterpart
  80. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  81. EP250226a / GRB 250226A: TRT optical counterpart observation
  82. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  83. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  84. EP250225a: GSP optical upper limit
  85. EP250223a: GMG Optical Observation
  86. EP250225a: Einstein Probe detected of a fast X-ray transient
  87. GRB 250225B: Swift detection of a burst
  88. EP250223a: GROWTH-India Telescope optical observations
  89. GRB 250221A: Swift-BAT refined analysis
  90. EP250215A: J band upper limit by SYSU 80cm telescope
  91. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  92. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  93. EP250223a: Kinder optical follow-up observations
  94. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  95. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  96. GRB 250119B: VZLUSAT-2 detection
  97. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  98. GRB 250202B: VZLUSAT-2 detection
  99. GRB 250222A: SVOM/GRM observation of a burst
  100. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading

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