Context : Classical novae are the product of thermonuclear runaway-initiated explosions occurring on accreting white dwarfs .

Aims : V339 Del ( Nova Delphinus 2013 ) was one of the brightest classical novae of the last hundred years .
Spectroscopy and photometry are available from \gamma -rays through infrared at stages that have frequently not been well observed .
The complete data set is intended to provide a benchmark for comparison with modeling and for understanding more sparsely monitored historical classical and recurrent novae .
This paper is the first in the series of reports on the development of the nova .
We report here on the early stages of the outburst , through the X-ray active stage .

Methods : A time sequence of optical , flux calibrated high resolution spectra was obtained with the Nordic Optical Telescope ( NOT ) using FIES simultaneously , or contemporaneously , with the Space Telescope Imaging Spectrograph ( STIS ) aboard the Hubble Space Telescope during the early stages of the outburst .
These were supplemented with MERCATOR/HERMES optical spectra .
High resolution IUE ultraviolet spectra of OS And 1986 , taken during the Fe curtain phase , served as a template for the distance determination .
We used standard plasma diagnostics ( e.g. , [ O III ] and [ N II ] line ratios , and the H \beta line flux ) to constrain electron densities and temperatures of the ejecta .
Using Monte Carlo modeling of the ejecta , we derived the structure , filling factor , and mass from comparisons of the optical and ultraviolet line profiles . Based on observations made with the NASA/ESA Hubble Space Telescope , obtained [ from the Data Archive ] at the Space Telescope Science Institute , which is operated by the Association of Universities for Research in Astronomy , Inc. , under NASA contract NAS 5-26555 .
These observations are associated with program # 13828 .

Results : We derive an extinction of E ( B-V ) =0.23 \pm 0.05 from the spectral energy distribution , the interstellar absorption , and H I emission lines .
The distance , about 4-4.5 kpc , is in agreement with the inferred distance from near infrared interferometry .
The maximum velocity was about 2500 km s ^ { -1 } , measured from the UV resonance and optical profiles .
The ejecta showed considerable fine structure in all transitions , much of which persisted as emission knots .
The line profiles were modeled using a bipolar conical structure for the ejecta within a relatively restricted range of parameters .
For V339 Del , we find that an inclination to the line of sight of about 35 ^ { o } -55 ^ { o } , an opening angle of 60 ^ { o } -80 ^ { o } , and an inner radius \Delta R / R ( t ) \approx 0.3 based on v _ { rad,max } matches the permitted and intercombination lines .
The filling factor is f \approx 0.1 , and the derived range in the ejecta mass is ( 2 - 3 ) \times 10 ^ { -5 } M _ { \odot } .

Conclusions :