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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28303 results found.

  1. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  2. EP250302a: SAO RAS optical observations
  3. EP250302a : GIT optical follow-up
  4. EP250225a: the candidate optical counterpart is an AGN
  5. EP250302a: Kinder optical follow-up observations
  6. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  7. EP250302a: Swift/UVOT detection
  8. EP250302a: optical observation from the INAF Asiago Observatory
  9. EP250302a: REM NIR upper limits
  10. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  11. EP250302a: Mondy Observations and Optical Light Curve
  12. EP250302a: VLT/MUSE optical redshift z = 1.131
  13. EP250302A: VLT near-infrared observations
  14. EP250302A: VLT/X-shooter tentative redshift
  15. EP250302a: OHP/T193 optical and spectroscopic observations
  16. EP250302a: Swift-XRT observations of a fading X-ray source
  17. EP250302a: Einstein Probe detection of an X-ray transient
  18. EP250302a: SVOM/C-GFT optical observations
  19. GRB 250226A: GRANDMA Optical Observations
  20. EP250302a: Montarrenti Observatory optical detection
  21. EP250302a: Nanshan/HMT optical counterpart detection
  22. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  23. GRB 250225B: VLT near-infrared afterglow confirmation
  24. EP250228a: Optical observations with Kinder and Swift/UVOT
  25. Konus-Wind detection of GRB 250226A
  26. GRB 250225B: EIRSAT-1 GMOD Detection
  27. GRB 250226A: KAO Optical Upper Limit
  28. GRB 250226A: AbAO AS-32 Optical Upper Limit
  29. EP250227a: Global MASTER-Net observations report
  30. EP250223A: Upper limits from Fermi-GBM Observations
  31. EP250227a: TRT optical upper limit
  32. GRB 250225B: VLT/HAWKI near-infrared observations
  33. EP250227a: Optical upper limits with Kinder observations
  34. EP250227a: NOT optical observations
  35. EP250227a: Einstein Probe detected of a fast X-ray transient
  36. EP250228a: updates on the EP observations
  37. GRB 250226A: Fermi GBM Observation
  38. EP250223a: J band upper limit by SYSU 80cm telescope
  39. EP250228a: Swift/XRT localisation
  40. EP250228a: Einstein Probe detection of an X-ray transient
  41. GRB 250226A / EP250226a: LCO detection of the afterglow
  42. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  43. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  44. GRB 250225B: VLT/Xshooter imaging
  45. GRB 250205A / EP250205A: further radio observations with the VLA
  46. EP250225a: NOT optical candidate counterpart
  47. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  48. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  49. EP250225a: TRT optical upper limits
  50. EP250226a/GRB 250226A: 1.6m Mephisto observations
  51. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  52. EP250226a/GRB 250226A: Kinder optical follow-up observations
  53. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  54. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  56. GRB 250225B: Fermi GBM Observation
  57. GRB 250225B: REM NIR upper limits
  58. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  59. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  60. EP250223a: CrAO ZTSH optical observation
  61. GRB 250225B: VLT optical and near-infrared candidate counterpart
  62. GRB 250225B: SVOM/GRM observation of a long burst
  63. EP250226a/GRB 250226A: GSP detects optical counterpart
  64. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  65. EP250226a / GRB 250226A: TRT optical counterpart observation
  66. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  67. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  68. EP250225a: GSP optical upper limit
  69. EP250223a: GMG Optical Observation
  70. EP250225a: Einstein Probe detected of a fast X-ray transient
  71. GRB 250225B: Swift detection of a burst
  72. EP250223a: GROWTH-India Telescope optical observations
  73. GRB 250221A: Swift-BAT refined analysis
  74. EP250215A: J band upper limit by SYSU 80cm telescope
  75. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  76. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  77. EP250223a: Kinder optical follow-up observations
  78. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  79. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  80. GRB 250119B: VZLUSAT-2 detection
  81. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  82. GRB 250202B: VZLUSAT-2 detection
  83. GRB 250222A: SVOM/GRM observation of a burst
  84. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  85. GRB 250206A: VZLUSAT-2 detection
  86. EP250223a: REM NIR upper limit
  87. EP250223a: TRT optical afterglow observation
  88. EP250223a: refined analysis of the EP-WXT and FXT observations
  89. EP250223a: 1.6m Mephisto and 50cm array observations
  90. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  91. 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
  92. EP250223a: OASDG optical observations
  93. EP250223a: LCO detection of the afterglow
  94. EP250223a: Swift/XRT localization
  95. EP250223a: NOT optical afterglow candidate
  96. EP250223a: Einstein Probe detection of an X-ray transient
  97. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  98. GRB 250221A: Optical counterpart detection by LCO.
  99. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  100. GRB 250221A: GRANDMA/TAROT Detection

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