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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').
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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"

42531 results found.

  1. GRID detection of GRB 250824A
  2. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  3. EP250827A: VLT/X-shooter redshift confirmation
  4. Fermi GRB 250827A: Global MASTER-Net observations report
  5. EP250827a: confirmation of optical rebrightening with LCO
  6. EP250827a: GOTO observation of the optical afterglow
  7. GRB 250826A: SVOM/GRM observation
  8. GRB 250827A: Fermi GBM Final Real-time Localization
  9. EP250827A: An optical rebrightening was detected by LCO.
  10. EP250827a: Swift-XRT counterpart detection
  11. The EP-WXT trigger 01709200800 is likely a flaring star
  12. EP250827a: TRT optical observations
  13. EP250827a: BOOTES-7 early optical dectection
  14. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  15. EP250827a: Gemini-South redshift z = 1.613
  16. EP250827a: Global MASTER-Net observations report
  17. EP250827a: Las Cumbres independent detection of the optical counterpart
  18. EP250827a: Gemini-South optical counterpart detection
  19. EP250827a: Einstein Probe detection of an X-ray transient
  20. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  21. Fermi GRB 250826A: Global MASTER-Net observations report
  22. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  23. EP250821a: Gemini GMOS Redshift Confirmation
  24. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  25. Fermi trigger No 777883624: Global MASTER-Net observations report
  26. GRB 250826A: Fermi GBM Final Real-time Localization
  27. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  28. Fermi GRB 250824B: Global MASTER-Net observations report
  29. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  30. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  31. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  32. GRB 250823A: Swift-BAT refined analysis
  33. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  34. GRB 250821B: AstroSat CZTI detection
  35. GRB 250819A: AstroSat CZTI detection
  36. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  37. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  38. GRB 250821B: Insight-HXMT detection
  39. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  40. GRB 250823A: Swift-XRT refined Analysis
  41. EP250821a: MeerKAT radio counterpart
  42. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars
  43. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  44. GRB 250824B: Fermi GBM Final Real-time Localization
  45. The EP-WXT trigger 01709200707 is likely a flaring star
  46. GRB 250823A: COLIBRÍ optical observations
  47. The EP-WXT trigger 01709200706 is likely a flaring star
  48. GRB 250823A: SVOM/VT optical observation
  49. GRB 250824A: Fermi GBM Final Real-time Localization
  50. GRB 250823A: Swift/UVOT Detection
  51. GRB 250823A: NOT optical observations
  52. LIGO/Virgo/KAGRA S250818k: CFH/MegaCam follow-up observation for AT2025ulz
  53. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  54. GRB 250823A: Fermi GBM Observation
  55. GRB 250818B: MeerKAT Detection
  56. GRB 250823A: Enhanced Swift-XRT position
  57. GRB 250823A: LCOGT Optical Detection
  58. GRB 250823A: BOOTES6/DPRT early optical detection
  59. GRB 250823A: Liverpool Telescope optical detection
  60. GRB 250823A: Swift detection of a burst
  61. GRB 250823A: Fermi GBM Final Real-time Localization
  62. Swift GRB250823.84: Global MASTER-Net observations report
  63. Konus-Wind detection of GRB 250821B
  64. LIGO/Virgo/KAGRA S250818k: Rebrightening detected with Gemini/GMOS
  65. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  66. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  67. LIGO/Virgo/KAGRA S250818k: PRIME nIR observations of AT2025ulz
  68. LIGO/Virgo/KAGRA S250818k: JinShan optical observations of AT2025ulz
  69. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  70. LIGO/Virgo/Kagra S250818k: STEP/T80N upper limits on 2025ulz
  71. LIGO/Virgo/KAGRA S250818k: 3 GHz MeerKAT observations of AT2025ulz
  72. GRB 250806A: Gemini observations of host galaxy candidate
  73. IPN triangulation of GRB 250821B (long/bright)
  74. GRB 250821A: Kilonova-Catcher optical upper limits
  75. EP250821a: Swift/XRT counterpart fading
  76. GRB 250812A: SVOM/ECLAIRs refined analysis
  77. GRB 250821A: Swift-BAT refined analysis
  78. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  79. LIGO/Virgo/KAGRA S250818k: NOT optical observations of AT2025ulz
  80. EP250821a: Swift/UVOT further observations.
  81. EP250821a: VLT X-shooter spectroscopic redshift z = 0.577
  82. LIGO/Virgo/KAGRA S250818k: GRAWITA TNG NIR observations of AT2025ulz
  83. GRB 250821A: VLT/FORS2 Optical Observation
  84. GRB 250821A: GECAM-B detection
  85. GRB 250821B: SVOM/GRM observation
  86. EP250821a: SVOM/VT optical observation
  87. Fermi GRB 250821B: Global MASTER-Net observations report
  88. GRB 250821A: NOT z-band upper limit
  89. GRB 250821C: Fermi GBM Final Real-time Localization
  90. GRB 250821A: KAIT optical upper limit
  91. LIGO/Virgo/KAGRA S250818k: Continued fading and reddening of AT2025ulz from Keck/LRIS imaging observations
  92. GRB 250821A: Swift-XRT refined Analysis
  93. Swift GRB 250821A: Global MASTER-Net observations report
  94. GRB 250821B: Fermi GBM Detection
  95. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of AT 2025ulz
  96. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  97. LIGO/Virgo/KAGRA S250818k : Tautenburg observations, upper limits
  98. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  99. GRB 250821A: Enhanced Swift-XRT position
  100. GRB 250821A: Swift/UVOT Upper Limits

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