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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').
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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"

19548 results found.

  1. GRB 251126A: further SAO RAS optical observations
  2. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  3. GRB251126A: MAO/AZT-22 optical observations
  4. GRB251126A: Continued optical observation from 1.3m DFOT
  5. GRB 251126A: Swift/UVOT Detection
  6. GRB 251126A: Mondy and SAO RAS optical observations
  7. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  8. GRB 251126A: 1.3m DFOT optical afterglow detection
  9. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  10. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  11. GRB 251126A: Enhanced Swift-XRT position
  12. GRB 251126A: Kilonova-Catcher optical afterglow detection
  13. GRB 251126A: Nanshan/HMT optical afterglow detection
  14. GRB 251126A: GIT discovery of the likely optical afterglow
  15. GRB 251126A: Swift detection of a burst
  16. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  17. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  18. EP251124b: NOT r- and z-band optical upper limits
  19. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  20. EP251124b: EP-WXT detection of a fast X-ray transient
  21. EP251124a: Xinglong GWAC-F60A optical observation
  22. EP251124a: NOT r- and z-band optical upper limits
  23. EP251124a: Swift-XRT observations
  24. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  25. EP251124a: Optical upper limit with Kinder observations
  26. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  27. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  28. EP251124a: GROWTH-India Telescope optical upper limits
  29. EP251124a: Einstein Probe detection of an X-ray transient
  30. GRB 251116C: Swift-XRT confirmation of fading
  31. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  32. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  33. EP251118A: 3.6m DOT optical afterglow detection
  34. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  35. GRB 251122A / EP251122a: WFST optical observations
  36. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  37. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  38. GRB 251122A / EP251122a: LCO optical upper limits
  39. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  40. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  41. GRB 251122A / EP251122a: SVOM detection of a long burst
  42. EP251122a: Einstein Probe detection of an X-ray transient
  43. EP251118a: Continued Optical Detection with Kinder observations
  44. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  45. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  46. EP251118a: Xinglong-2.16m optical observation
  47. Fermi trigger No 785388351: Global MASTER-Net observations report
  48. EP251118A: 1.3m DFOT optical afterglow detection
  49. GRB 251118A: Swift/UVOT Detection
  50. EP251118a / GRB 251118C: SAO RAS optical observations
  51. GRB 251118A: Swift-XRT afterglow detection
  52. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  53. EP251118a: Optical detection with Kinder observations
  54. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  55. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  56. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  57. GRB 251117A: Swift-XRT observations
  58. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  59. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  60. EP251118a: VLT near-infrared observation
  61. GRB 251116D: SVOM/GRM observation of a long GRB
  62. GRB 251119A: SVOM detection of a possible burst
  63. EP251118a: NOT candidate optical counterpart
  64. GRB 251118A: Swift ToO observations
  65. EP251118a: Einstein Probe detected of a fast X-ray transient
  66. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  67. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  68. GRB 251117A: SVOM/GRM observation of a short burst
  69. GRB 251117A: Tiled Swift observations
  70. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  72. EP251023a: Assy AZT-20 optical observations
  73. EP251023a: UAFO and AbAO optical observations
  74. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  75. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  76. GRB 251025B: further Mondy optical observations
  77. GRB 251111A: Mondy optical upper limit
  78. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  80. GRB 251116B: LCO optical upper limits
  81. GRB 251116C: LCO optical upper limits
  82. GRB 251116B: SVOM detection of a burst
  83. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  84. GRB 251115A: Tiled Swift observations
  85. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  86. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  87. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  88. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  89. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  90. GRB 251112A: Swift/UVOT Upper Limits
  91. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  92. Swift Trigger 1413695: a possible GRB 251112A
  93. GRB251111A: 1.3m DFOT optical upper limit
  94. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  95. GRB 251111A: Swift-XRT afterglow detection
  96. GRB 251111A: SVOM/VT optical observations with X-band data
  97. GRB 251111A: SVOM/VT optical observations with VHF data
  98. GRB 251111A: LCO optical observation
  99. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  100. GRB 251106A: Swift/UVOT Upper Limits

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