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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"

23574 results found.

  1. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  2. EP 250304A: Optical counterpart detection by LCO
  3. EP250302A: 1.3m DFOT optical afterglow detection
  4. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP250304a: REM NIR upper limits
  6. IPN triangulation of GRB 250222A
  7. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  8. EP250302a: Mondy Continued Optical Observations
  9. EP250304a: Swift-XRT detection of a fading X-ray source
  10. EP250304a: TRT optical counterpart detection
  11. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  12. EP250304a: Einstein Probe detection of an X-ray transient
  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: Kinder optical follow-up observations
  17. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  18. EP250302a: Swift/UVOT detection
  19. EP250302a: optical observation from the INAF Asiago Observatory
  20. EP250302a: REM NIR upper limits
  21. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  22. EP250302a: Mondy Observations and Optical Light Curve
  23. EP250302a: VLT/MUSE optical redshift z = 1.131
  24. EP250302A: VLT near-infrared observations
  25. EP250302A: VLT/X-shooter tentative redshift
  26. EP250302a: OHP/T193 optical and spectroscopic observations
  27. EP250302a: Einstein Probe detection of an X-ray transient
  28. EP250302a: SVOM/C-GFT optical observations
  29. GRB 250226A: GRANDMA Optical Observations
  30. EP250302a: Montarrenti Observatory optical detection
  31. EP250302a: Nanshan/HMT optical counterpart detection
  32. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  33. GRB 250225B: VLT near-infrared afterglow confirmation
  34. EP250228a: Optical observations with Kinder and Swift/UVOT
  35. GRB 250226A: KAO Optical Upper Limit
  36. GRB 250226A: AbAO AS-32 Optical Upper Limit
  37. EP250227a: TRT optical upper limit
  38. GRB 250225B: VLT/HAWKI near-infrared observations
  39. EP250227a: Optical upper limits with Kinder observations
  40. EP250227a: NOT optical observations
  41. EP250227a: Einstein Probe detected of a fast X-ray transient
  42. EP250228a: updates on the EP observations
  43. EP250225a: EP-FXT follow-up observation
  44. EP250223a: J band upper limit by SYSU 80cm telescope
  45. EP250228a: Einstein Probe detection of an X-ray transient
  46. GRB 250225B: VLT/Xshooter imaging
  47. GRB 250205A / EP250205A: further radio observations with the VLA
  48. GRB 250225B: INTEGRAL SPI-ACS detection
  49. EP250225a: NOT optical candidate counterpart
  50. EP250226a/GRB 250226A:Xinglong optical follow-up 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 S250227e: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  58. GRB 250221A: ATCA Detections and Upper Limits
  59. GRB 250225B: REM NIR upper limits
  60. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  61. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  62. EP250223a: CrAO ZTSH optical observation
  63. GRB 250225B: VLT optical and near-infrared candidate counterpart
  64. GRB 250225B: VLT/FORS2 candidate optical afterglow
  65. GRB 250225B: SVOM/GRM observation of a long burst
  66. EP250226a/GRB 250226A: GSP detects optical counterpart
  67. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  68. EP250226a / GRB 250226A: TRT optical counterpart observation
  69. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  70. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  71. EP250223a: GMG Optical Observation
  72. EP250225a: Einstein Probe detected of a fast X-ray transient
  73. GRB 250225B: Swift detection of a burst
  74. EP250223a: GROWTH-India Telescope optical observations
  75. EP250215A: J band upper limit by SYSU 80cm telescope
  76. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  77. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  78. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  79. EP250223a: Kinder optical follow-up observations
  80. GRB 250207a: ATCA Radio Upper Limits
  81. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  82. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  83. GRB 250222A: SVOM/GRM observation of a burst
  84. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  85. EP250223a: REM NIR upper limit
  86. EP250223a: TRT optical afterglow observation
  87. EP250223a: refined analysis of the EP-WXT and FXT observations
  88. EP250223a: 1.6m Mephisto and 50cm array observations
  89. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  90. 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
  91. EP250223a: OASDG optical observations
  92. EP250223a: NOT optical afterglow candidate
  93. EP250223a: Einstein Probe detection of an X-ray transient
  94. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  95. GRB 250221A: Optical counterpart detection by LCO.
  96. EP250220a: EP-FXT follow-up observations
  97. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  98. GRB 250221A: GRANDMA/TAROT Detection
  99. GRB 250221A: Swift-XRT refined Analysis
  100. GRB 250221A: 1.6m Mephisto optical detection

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