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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"

32550 results found.

  1. GRB 250329B: SVOM/VT optical upper limit
  2. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  3. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  4. GRB250329A: REM optical afterglow detection
  5. GRB 250329B: GWAC-F50A optical upper limit
  6. GRB 250329A: Swift-XRT afterglow detection
  7. GRB 250328A: SVOM/VT optical observation
  8. GRB 250329A: Fading optical counterpart detection by LCO.
  9. GRB 250328A: SVOM/C-GFT optical upper limit
  10. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  11. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  12. GRB 250329A: VLT/X-shooter redshift z = 2.921
  13. GRB 250329A: SVOM/VT optical counterpart confirmation
  14. GRB 250327B: J-band observations with WINTER
  15. GRB 250327B: MASTER detection of OT rebrightening
  16. GRB 250327B: LCO optical counterpart detection
  17. GRB 250328A: GWAC-F50A optical upper limit
  18. FRB 20250316A: FTW optical observations
  19. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  20. GRB 250327B: CrAO and SAO RAS Optical Observations
  21. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  22. GRB 250327B: further optical observations by LCOGT
  23. EP250315a: Pan-STARRS r and i-band imaging and photometry
  24. GRB 250327b: Liverpool Telescope optical observations
  25. GRB 250322A: GRANDMA/TNOT optical upper limits
  26. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  27. GRB 250327A: SVOM/VT upper limits on the XRT position
  28. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  29. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  30. GRB 250327B: Las Cumbres optical counterpart detection
  31. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  32. GRB 250327B: 1.6m Mephisto optical observations
  33. GRB 250327B: NOT spectroscopic redshift z = 3.035
  34. GRB 250327B: GOTO optical counterpart detection
  35. GRB 250327B: SVOM/VT optically bright counterpart
  36. GRB 250327B: SAO RAS optical candidate
  37. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  38. GRB 250327A: J-band observations with WINTER
  39. GRB 250327A: SVOM/VT optical candidate
  40. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  41. GRB 250327A: Fermi GBM observation
  42. Fermi GRB 250327A: Global MASTER-Net observations report
  43. Swift GRB 250327A: Global MASTER-Net observations report
  44. GRB 250327A: DDOTI Optical Observations
  45. GRB 250327A: COLIBRÍ optical upper limit
  46. GRB 250327A: Swift detection of a burst
  47. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  48. Konus-Wind detection of GRB 250322A (short)
  49. IPN triangulation of GRB 250322B
  50. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  51. EP250321a: Mondy AZT-33IK Continued Optical Observations
  52. GRB 250322A: third epoch of NOT optical observations
  53. GRB 250322A: Swift-BAT refined analysis
  54. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  55. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  56. GRB 250322A: further NOT optical observations
  57. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  58. GRB 250322A: Swift/UVOT Upper Limits
  59. GRB 250322A: VLT/X-shooter redshift confirmation of the putative host galaxy
  60. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  61. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  62. EP250321a: TNOT Observation of Optical Counterpart
  63. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  64. GRB 250322A: Gemini-North redshift of candidate host galaxy
  65. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  66. GRB 250322A: AstroSat CZTI detection of a short burst
  67. GRB250322A: STEP/T80S optical limits
  68. GRB 250322A: Gemini-South optical observations
  69. GRB 250322A: VLT optical observations
  70. GRB 250322A: VLT near-infrared observations
  71. FRB 250316A: DDOTI Continued Optical Observations
  72. GRB 250322A: NOT optical upper limits
  73. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  74. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  75. GRB 250322A: MASTER optical observation
  76. EP250321a: Liverpool Telescope optical follow-up
  77. EP250321a: Mondy AZT-33IK Optical Observations
  78. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  79. EP250321a: KAIT optical observations
  80. EP250321A: COLIBRÍ Continuing Optical Observations
  81. GRB 250225B: GECAM-A detection
  82. GRB 250312A: GECAM-A detection
  83. GRB 250321B: Swift ToO observations
  84. EP250321a: WFST optical observations
  85. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  86. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  87. GRB 250320B: Fermi GBM Observation
  88. EP250321a: Xinglong 216 decaying optical observations
  89. GRB 250321A: Swift-BAT refined analysis
  90. GRB 250320B: Fermi-LAT detection
  91. EP250321a: SVOM/VT optical observation
  92. EP 250321A: Optical counterpart detection by LCO.
  93. EP250321a: Kinder optical follow-up observations
  94. GRB 250321A: Swift/UVOT Upper Limits
  95. GRB 250320B: SVOM/GRM observation of a long burst
  96. EP250321a: LCO optical counterpart detection
  97. EP250321a: Swift-XRT detection of an X-ray source
  98. EP250321A: COLIBRÍ Optical Observations
  99. EP250321a: VLT/X-shooter redshift z = 4.368
  100. GRB 250320B: AstroSat CZTI detection

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