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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"

15402 results found.

  1. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  2. GRB 250831A: Swift-XRT counterpart detection
  3. GRB 250831A: SVOM detection of a soft burst
  4. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  5. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  6. GRB 250830B: Swift ToO observations
  7. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  8. EP250821a: SOAR observations
  9. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  10. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  11. GRB 250808B: SVOM detection of a burst through offline search
  12. EP250828a: Liverpool Telescope upper limits
  13. EP250828a: KAIT optical upper limit
  14. EP250828a: NOT optical counterpart confirmation
  15. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  16. EP250827A: VLT/X-shooter redshift confirmation
  17. EP250827a: confirmation of optical rebrightening with LCO
  18. GRB 250826A: SVOM/GRM observation
  19. EP250827A: An optical rebrightening was detected by LCO.
  20. EP250827a: Swift-XRT counterpart detection
  21. EP250827a: BOOTES-7 early optical dectection
  22. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  23. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  24. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  25. GRB 250821B: AstroSat CZTI detection
  26. GRB 250819A: AstroSat CZTI detection
  27. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  28. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  29. GRB 250821B: Insight-HXMT detection
  30. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  31. GRB 250823A: COLIBRÍ optical observations
  32. LIGO/Virgo/KAGRA S250818k: CFH/MegaCam follow-up observation for AT2025ulz
  33. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  34. GRB 250823A: Fermi GBM Observation
  35. GRB 250823A: BOOTES6/DPRT early optical detection
  36. Konus-Wind detection of GRB 250821B
  37. LIGO/Virgo/KAGRA S250818k: Rebrightening detected with Gemini/GMOS
  38. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  39. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  40. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  41. LIGO/Virgo/Kagra S250818k: STEP/T80N upper limits on 2025ulz
  42. GRB 250806A: Gemini observations of host galaxy candidate
  43. EP250821a: Swift/XRT counterpart fading
  44. GRB 250812A: SVOM/ECLAIRs refined analysis
  45. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  46. EP250821a: Swift/UVOT further observations.
  47. GRB 250821A: GECAM-B detection
  48. GRB 250821B: SVOM/GRM observation
  49. GRB 250821A: NOT z-band upper limit
  50. GRB 250821A: KAIT optical upper limit
  51. LIGO/Virgo/KAGRA S250818k: Continued fading and reddening of AT2025ulz from Keck/LRIS imaging observations
  52. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of AT 2025ulz
  53. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  54. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  55. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  56. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  57. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  58. GRB 250819A: Insight-HXMT detection
  59. LIGO/Virgo/KAGRA S250818k: Pan-STARRS grizy-band imaging and photometry of AT2025ulz
  60. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  61. LIGO/Virgo/KAGRA S250818k: Multi-band Gemini GMOS Detections
  62. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz
  63. GRB 250818B: Kilonova-Catcher optical afterglow detection
  64. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  65. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  66. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  67. GRB 250818A: AstroSat CZTI detection
  68. LIGO/Virgo/KAGRA S250818k: Properties of the low-significance GW compact binary merger candidate potentially associated with AT 2025ulz
  69. LIGO/Virgo/KAGRA S250818k: FTW Fast reddening of AT 2025ulz
  70. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  71. GRB 250818B: EP-FXT counterpart detection
  72. LIGO/Virgo/KAGRA S250818k: FTW optical and NIR observations of AT 2025ulz
  73. LIGO/Virgo/KAGRA S250818k: Candidates from the Zwicky Transient Facility
  74. GRB 250813B: SVOM/ECLAIRs refined analysis
  75. GRB 250818A: Fermi GBM Observation
  76. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  77. GRB 250814A: Further GRAWITA TNG NIR observations
  78. GRB 250818B: Swift-XRT afterglow detection
  79. GRB 250818B: SVOM detection of a short burst
  80. GRB 250816A: SVOM/GRM observation of a short burst
  81. SVOM/sb25081602: detection of a likely X-ray transient
  82. GRB 250814A: GRAWITA TNG NIR observations
  83. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  84. GRB 250814B: SVOM/GRM observation
  85. GRB 250814C: SVOM/GRM observation of a short burst
  86. GRB 250813B: SVOM/GRM observation
  87. GRB 250814A: P200/WIRC observations of the afterglow candidate
  88. GRB 250814A: KAIT optical upper limit
  89. GRB 240814A: Fermi GBM Observation
  90. GRB 250814A: Possible afterglow candidate from P200/WIRC
  91. GRB 250813B: Fermi GBM Observation
  92. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  93. GRB 250814A: J-band upper limit from WINTER
  94. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  95. GRB 250813B: NOT observations of the optical afterglow
  96. Subject GRB 250813B: SVOM/MXT refined analysis
  97. GRB 250814A: COLIBRÍ optical upper limit
  98. GRB 250813A: AstroSat CZTI detection
  99. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  100. GRB 250813B: EP-FXT counterpart detection

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